chore: scaffold tvctl foundation

Set up the Rust crate, baseline module layout, and project docs so the
repository matches the design bundle and builds cleanly as a starting point.

docs/ADAPTER.md

@@ -0,0 +1,33 @@
+# ADAPTER.md
+# tvctl Adapter Contract
+
+The adapter layer isolates platform-specific TV control protocols from the
+rest of `tvctl`. Everything above this layer speaks the normalized tvctl
+data model; everything below it speaks the platform's native protocol.
+
+## Required Trait
+
+The canonical trait lives in `src/adapters/mod.rs`:
+
+```rust
+pub trait TvAdapter: Send + Sync {
+    async fn discover(&self) -> Result<Vec<DeviceInfo>>;
+    async fn state(&self, device: &Device) -> Result<DeviceState>;
+    async fn launch(&self, device: &Device, app: &str) -> Result<()>;
+    async fn stop_app(&self, device: &Device) -> Result<()>;
+    async fn key(&self, device: &Device, key: TvKey) -> Result<()>;
+    async fn sequence(&self, device: &Device, keys: Vec<TvKey>) -> Result<()>;
+    async fn list_apps(&self, device: &Device) -> Result<Vec<AppInfo>>;
+    async fn dev_install(&self, device: &Device, zip: &[u8]) -> Result<()>;
+    async fn dev_reload(&self, device: &Device) -> Result<()>;
+    async fn dev_logs(&self, device: &Device) -> Result<Vec<String>>;
+}
+```
+
+## Rules
+
+- The adapter surface is the boundary between normalized and platform data.
+- Adapters translate normalized `TvKey` values into platform-specific input.
+- Platform support belongs in a dedicated subdirectory under `src/adapters/`.
+- Dev-mode methods may return `NotSupported` when a platform lacks that feature.
+- The CLI, daemon, and HTTP API must not contain platform-specific logic.