feat(daemon): add GET /status endpoint (bd-148)

- Add OpStatus operation and StatusResponse type to RPC protocol
- Add workspacePath and dbPath fields to Server struct
- Implement handleStatus() handler with daemon metadata
- Track last activity time with atomic.Value
- Add client.Status() method
- Check for exclusive locks via ShouldSkipDatabase()
- Update all test files to use new NewServer signature
- Add comprehensive status endpoint test

Closes bd-148

internal/rpc/bench_test.go

@@ -285,7 +285,7 @@ func setupBenchServer(b *testing.B) (*Server, *Client, func(), string) {
 		b.Fatalf("Failed to create store: %v", err)
 	}
 
-	server := NewServer(socketPath, store)
+	server := NewServer(socketPath, store, tmpDir, dbPath)
 
 	ctx, cancel := context.WithCancel(context.Background())
 	go func() {