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>

Cargo.lock

@@ -179,7 +179,7 @@ checksum = "d9c4f5dac5e15c24eb999c26181a6ca40b39fe946cbe4c263c7209467bc83af2"
 
 [[package]]
 name = "gamewrap"
-version = "0.3.0"
+version = "1.0.0"
 dependencies = [
  "clap",
  "clap_complete",