Add RPC support for compact command (bd-184)

- Added OpCompact and OpCompactStats operation constants
- Added CompactArgs, CompactStatsArgs, and response types to RPC protocol
- Implemented handleCompact and handleCompactStats in RPC server
- Updated compact command to use RPC when daemon is available
- Fixed RPC client to include Cwd for proper database routing
- Compact now works in daemon mode with --no-daemon flag

Amp-Thread-ID: https://ampcode.com/threads/T-87885d07-80ad-466d-9ffb-cc96fab4853f
Co-authored-by: Amp <amp@ampcode.com>

internal/rpc/client.go

@@ -99,10 +99,14 @@ func (c *Client) Execute(operation string, args interface{}) (*Response, error)
 		return nil, fmt.Errorf("failed to marshal args: %w", err)
 	}
 
+	// Get current working directory for database routing
+	cwd, _ := os.Getwd()
+
 	req := Request{
 		Operation:     operation,
 		Args:          argsJSON,
 		ClientVersion: ClientVersion,
+		Cwd:           cwd,
 	}
 
 	reqJSON, err := json.Marshal(req)