feat: hook reliability, hook-errors setting, sparse config, and logging

Hook reliability:
- Add hook-errors = "warn" | "fail" setting (default: warn); in fail
  mode, abort launch when pre-launch hook exits nonzero or can't execute
- Ensure post-launch hook runs unconditionally, even when execute_wait()
  fails to spawn the game
- Propagate game's real exit status via std::process::exit(); report
  post-hook failures clearly to stderr
- Centralize hook execution via run_hook() helper (sh -c)

New features in this batch:
- Sparse config and profile support: only configured fields are written;
  unset fields fall back through profile → global chain
- config show --effective flag: renders the fully-resolved view
- Config migration: upgrades legacy flat config to current schema
- Structured decision logging (src/log.rs) for session-level audit trail
- Gamescope improvements: additional flags and validation
- CHANGELOG.md tracking template releases

Schema / UX:
- HookErrors enum (Warn/Fail) added to Settings and ResolvedSettings
- hook-errors key in keys.rs, mod.rs rendering, completion candidates,
  doctor output, help text, README, and dry-run display
- 9 focused tests covering warn/fail behavior, exit propagation,
  round-trip (set/show/reset), profile round-trip, export/import

Co-Authored-By: claude-flow <ruv@ruv.net>

README.md

@@ -19,10 +19,10 @@ gamewrap %command%
 ## Features
 
 - Short Steam launch options
-- Friendly setting names like `overlay` and `performance`
+- Friendly setting names like `mangohud` and `gamemode`
 - Persistent config outside the Steam UI
 - Named profiles for reusable setups
-- Profile inheritance for layered setups
+- Flat game-specific profiles layered on global defaults
 - Game-specific profile binding through `game bind`
 - Quick access to the last played game through `gamewrap last`
 - Play time and launch count tracking per game
@@ -32,7 +32,6 @@ gamewrap %command%
 - Config export/import for backup and sharing
 - Direct config editing through `config edit`
 - Profile export/import for sharing one setup at a time
-- Profile tree view for inheritance checks
 - Per-profile environment variable overrides
 - gamescope Wayland compositor integration
 - FPS cap through MangoHud
@@ -97,13 +96,13 @@ $HOME/.cargo/bin/gamewrap %command%
 2. Turn MangoHud on by default:
 
 ```bash
-gamewrap config set overlay on
+gamewrap config set mangohud on
 ```
 
 3. Turn GameMode on by default:
 
 ```bash
-gamewrap config set performance on
+gamewrap config set gamemode on
 ```
 
 4. Check your setup before launching a real game:
@@ -133,13 +132,11 @@ gamewrap profile create benchmark
 gamewrap game bind "Game.exe" benchmark
 ```
 
-8. Layer one profile on top of another when you want shared defaults:
+8. Add game-specific overrides while keeping shared values global:
 
 ```bash
-gamewrap profile create base
-gamewrap profile set base overlay on
+gamewrap config set mangohud on
 gamewrap profile create benchmark
-gamewrap profile inherit benchmark base
 gamewrap profile set benchmark verbose on
 ```
 
@@ -181,6 +178,8 @@ gamewrap run -- /path/to/game/executable
 ```bash
 gamewrap --help
 gamewrap help settings
+gamewrap help settings gamescope
+gamewrap help settings mangohud
 gamewrap help doctor
 gamewrap game list
 gamewrap game list "elden"
@@ -196,20 +195,23 @@ gamewrap completion zsh
 gamewrap completion install zsh
 gamewrap completion path zsh
 gamewrap config show
+gamewrap config show --effective
 gamewrap config edit
+gamewrap config reset --all
+gamewrap config migrate
 gamewrap config export shared
 gamewrap config import shared
 gamewrap last
 gamewrap profile list
-gamewrap profile tree
 gamewrap profile create benchmark
+gamewrap profile show benchmark
+gamewrap profile show benchmark --effective
 gamewrap profile duplicate benchmark benchmark-copy
-gamewrap profile inherit benchmark base
-gamewrap profile clear-inherit benchmark
 gamewrap profile export benchmark benchmark
 gamewrap profile import benchmark
-gamewrap profile set benchmark overlay on
-gamewrap profile reset benchmark overlay
+gamewrap profile migrate old-benchmark
+gamewrap profile set benchmark mangohud on
+gamewrap profile reset benchmark mangohud
 gamewrap profile env set benchmark DXVK_ASYNC 1
 gamewrap profile env list benchmark
 gamewrap profile env unset benchmark DXVK_ASYNC
@@ -222,15 +224,20 @@ gamewrap game clear-note "eldenring.exe"
 
 ## Friendly Settings
 
-- `overlay`: turns MangoHud on or off
-- `performance`: turns GameMode on or off
+- `mangohud`: turns MangoHud on or off
+- `gamemode`: turns GameMode on or off
 - `steam-host-libs`: prefers host libraries inside Steam runtime environments and sets `STEAM_RUNTIME_PREFER_HOST_LIBRARIES=1`
 - `game-libs`: controls whether `gamewrap` injects auto-detected host library directories into `LD_LIBRARY_PATH`
 - `verbose`: shows more detail in diagnostic commands
+- `log-file`, `log-path`: append gamewrap launch decisions to the default state log or a custom path
 - `gamescope`: wraps the game in the gamescope Wayland compositor
-- `gamescope-width`, `gamescope-height`, `gamescope-fps`: pass `-W`, `-H`, and `-r` values to gamescope when `gamescope` is on
-- `fps-cap`: caps frame rate through MangoHud when `overlay` is on, for example `gamewrap config set fps-cap 60`
+- `gamescope-width`, `gamescope-height`: set output resolution with a pixel count or `native`; unset uses gamescope's 1280x720 default
+- `gamescope-mode`: selects `windowed`, `borderless`, or `fullscreen`
+- `gamescope-fps`: passes the `-r` target refresh value when gamescope is on
+- `fps-cap`: caps frame rate through MangoHud when `mangohud` is on, for example `gamewrap config set fps-cap 60`
+- `mangohud-log`, `mangohud-log-path`: enable full-session MangoHud performance logging and optionally choose its output path
 - `vkbasalt`: enables vkBasalt post-processing with `ENABLE_VKBASALT=1`
+- `vkbasalt-log-level`: sets `VKBASALT_LOG_LEVEL` to `debug`, `info`, `warning`, `error`, or `none` when vkBasalt is on
 - `esync`: forces Proton esync on or off with `PROTON_NO_ESYNC`; leave unset to use Steam/Proton defaults
 - `fsync`: forces Proton fsync on or off with `PROTON_NO_FSYNC`; leave unset to use Steam/Proton defaults
 - `large-address-aware` / `laa`: sets `PROTON_LARGE_ADDRESS_AWARE=1` for older 32-bit Proton games that need more than 2 GB of address space
@@ -238,9 +245,20 @@ gamewrap game clear-note "eldenring.exe"
 - `post-launch`: runs a shell command after the game exits; when set, gamewrap spawns the game and waits for it to finish before running this hook
 - `env-vars`: per-profile environment overrides managed with `gamewrap profile env set/list/unset/clear`
 
+**hook-errors** (`warn` | `fail`, default: `warn`)
+
+Controls what happens when a pre-launch hook exits nonzero or cannot be executed.
+- `warn` — a message is printed to stderr and the game launches anyway.
+- `fail` — gamewrap aborts with an error and the game is not launched.
+
+The post-launch hook always runs after the pre-launch hook succeeds, even if the game itself fails to start.
+
+Example:
+  gamewrap config set hook-errors fail
+
 ## How It Works
 
-When `gamewrap` launches a game, it resolves your defaults, any inherited profile chain, and any matching game binding, prepares the needed environment variables, and then prefixes the game command with `gamescope`, `mangohud`, and/or `gamemoderun` when those features are enabled.
+When `gamewrap` launches a game, it applies global defaults, then any matching profile overrides, prepares the needed environment variables, and prefixes the game command with `gamescope`, `mangohud`, and/or `gamemoderun` when those features are enabled.
 
 If something important is missing, `gamewrap` is designed to fail clearly instead of silently skipping the requested behavior. The `doctor` and `status` commands help you verify that before launching through Steam.
 
@@ -253,7 +271,6 @@ For terminal usage, `gamewrap` distinguishes between management commands and exp
 - `gamewrap config edit` opens the config file in `$VISUAL`, `$EDITOR`, or `nano`
 - use `gamewrap config export` and `gamewrap config import ...` for full-config backup and sharing
 - use `gamewrap profile export` and `gamewrap profile import ...` for sharing one profile
-- use `gamewrap profile tree` to inspect profile inheritance
 - use `gamewrap profile env set <profile> <KEY> <VALUE>` for per-profile environment overrides
 - use `gamewrap notify test` to verify graphical failure notifications
 - use `gamewrap run <command>` when you want to explicitly launch from the terminal
@@ -302,9 +319,9 @@ gamewrap profile import benchmark
 
 `gamewrap` automatically adds `.gamewrap.toml` or `.gamewrap-profile.toml` when needed.
 
-`gamewrap config export` writes resolved settings, not just the sparse internal overrides. That makes the exported file more predictable when you import it on another machine with different defaults.
+`gamewrap config export` writes the sparse global defaults and profile overrides exactly as configured.
 
-`gamewrap profile export` also writes resolved settings. Imported profiles are brought in as standalone profiles with explicit values, so they keep the same behavior even if the importing machine uses different defaults.
+`gamewrap profile export` writes only explicitly configured profile settings. Imported profiles use the receiving machine's global defaults for every unset value.
 
 ## Files