feat: adapt to OpenCode v2 plugin API (>=1.17.10) with event/dispose hooks

Author: Cle2ment

AGENTS.md

@@ -37,22 +37,23 @@ npx @agentmemory/agentmemory  (CLI + worker, ~15-30s startup)
 - **Engine version pin**: agentmemory pins iii-engine to v0.11.2 (v0.11.6+ has incompatible sandbox model).
 - **Windows**: no binary auto-download; Docker fallback needed.
 
-## Plugin API Compliance
+## Plugin API Compliance (v2)
 
-Per [OpenCode Plugin API](https://opencode.ai/docs/en/plugins/) — `@opencode-ai/plugin` v1.15+ (Hooks interface):
+Per [OpenCode Plugin API v2](https://opencode.ai/docs/en/plugins/) — `@opencode-ai/plugin` >=1.17.10 (Effect + Promise plugins):
 
+- **`Plugin` signature**: `(input: PluginInput, options?: PluginOptions) => Promise<Hooks>`. `PluginInput` includes `client`, `project`, `directory`, `worktree`, `serverUrl`, etc.
 - **`config` hook**: called on every config load. Guard with `if (!timer)` for once-only init. Signature: `config?: (input: Config) => Promise<void>`.
-- **`event` hook**: subscribe to lifecycle events including `server.instance.disposed`. Use for cleanup.
-- **`timer.unref()`**: mark the health-check interval as non-blocking so it never prevents the Node process from exiting. Replaces the need for a `dispose` hook.
-- **`dispose` does NOT exist**: the OpenCode `Hooks` interface has no `dispose` property. DO NOT return a `dispose` property from the plugin function — it will never be called. Use `timer.unref()` + the `event` hook instead.
+- **`event` hook**: subscribe to lifecycle events including `server.instance.disposed`. Use for cleanup alongside `timer.unref()`.
+- **`dispose` hook**: **NEW in v1.17.10+**. Called when the server shuts down. Use for deterministic cleanup.
+- **`timer.unref()`**: mark the health-check interval as non-blocking so it never prevents the Node process from exiting.
 - **`client.app.log()`**: Use for structured logging, not `console.error`.
 
 ## Conventions
 
 - TypeScript strict — no `any`, no `@ts-ignore`
 - Single export: `AgentmemoryLauncherPlugin: Plugin`
 - Stateless — process supervision via `child.unref()`, no file I/O
-- Runtime dependency: only `@opencode-ai/plugin` (devDeps in `package.json`)
+- Runtime dependency: only `@opencode-ai/plugin` (>=1.17.10)
 
 ## CI/CD