refactor: require Bun globally, add auto-install, remove Windows executable approach (#243)

- Delete BinaryManager.ts - no longer needed
- Simplify ProcessManager.ts - single Bun spawn path for all platforms
- Update smart-install.js - auto-install Bun if missing (Windows/Unix)
- Update documentation to reflect Bun requirement

This simplifies the codebase by:
- Using Bun consistently across all platforms (hooks + worker)
- Eliminating binary download/hosting complexity
- Zero native dependencies with bun:sqlite
- Auto-installing Bun on first run if not present

Co-authored-by: Claude <noreply@anthropic.com>

docs/public/architecture/worker-service.mdx

@@ -1,16 +1,17 @@
 ---
 title: "Worker Service"
-description: "HTTP API and PM2 process management"
+description: "HTTP API and Bun process management"
 ---
 
 # Worker Service
 
-The worker service is a long-running HTTP API built with Express.js and managed by PM2. It processes observations through the Claude Agent SDK separately from hook execution to prevent timeout issues.
+The worker service is a long-running HTTP API built with Express.js and managed natively by Bun. It processes observations through the Claude Agent SDK separately from hook execution to prevent timeout issues.
 
 ## Overview
 
 - **Technology**: Express.js HTTP server
-- **Process Manager**: PM2
+- **Runtime**: Bun (auto-installed if missing)
+- **Process Manager**: Native Bun process management via ProcessManager
 - **Port**: Fixed port 37777 (configurable via `CLAUDE_MEM_WORKER_PORT`)
 - **Location**: `src/services/worker-service.ts`
 - **Built Output**: `plugin/scripts/worker-service.cjs`
@@ -322,28 +323,15 @@ DELETE /sessions/:sessionDbId
 
 **Note**: As of v4.1.0, the cleanup hook no longer calls this endpoint. Sessions are marked complete instead of deleted to allow graceful worker shutdown.
 
-## PM2 Management
+## Bun Process Management
 
-### Configuration
+### Overview
 
-The worker is configured via `ecosystem.config.cjs`:
-
-```javascript
-module.exports = {
-  apps: [{
-    name: 'claude-mem-worker',
-    script: './plugin/scripts/worker-service.cjs',
-    instances: 1,
-    autorestart: true,
-    watch: false,
-    max_memory_restart: '1G',
-    env: {
-      NODE_ENV: 'production',
-      FORCE_COLOR: '1'
-    }
-  }]
-};
-```
+The worker is managed by the native `ProcessManager` class which handles:
+- Process spawning with Bun runtime
+- PID file tracking at `~/.claude-mem/worker.pid`
+- Health checks with automatic retry
+- Graceful shutdown with SIGTERM/SIGKILL fallback
 
 ### Commands
 
@@ -366,7 +354,18 @@ npm run worker:status
 
 ### Auto-Start Behavior
 
-As of v4.0.0, the worker service auto-starts when the SessionStart hook fires. Manual start is optional.
+The worker service auto-starts when the SessionStart hook fires. Manual start is optional.
+
+### Bun Requirement
+
+Bun is required to run the worker service. If Bun is not installed, the smart-install script will automatically install it on first run:
+
+- **Windows**: `powershell -c "irm bun.sh/install.ps1 | iex"`
+- **macOS/Linux**: `curl -fsSL https://bun.sh/install | bash`
+
+You can also install manually via:
+- `winget install Oven-sh.Bun` (Windows)
+- `brew install oven-sh/bun/bun` (macOS)
 
 ## Claude Agent SDK Integration
 
@@ -410,15 +409,15 @@ If port 37777 is in use, the worker will fail to start. Set a custom port via en
 
 ## Data Storage
 
-The worker service stores data in the plugin data directory:
+The worker service stores data in the user data directory:
 
 ```
-${CLAUDE_PLUGIN_ROOT}/data/
-├── claude-mem.db           # SQLite database
-├── worker.port             # Current worker port file
+~/.claude-mem/
+├── claude-mem.db           # SQLite database (bun:sqlite)
+├── worker.pid              # PID file for process tracking
+├── settings.json           # User settings
 └── logs/
-    ├── worker-out.log      # Worker stdout logs
-    └── worker-error.log    # Worker stderr logs
+    └── worker-YYYY-MM-DD.log  # Daily rotating logs
 ```
 
 ## Error Handling