feat(battleship): add full placement/battle phases + metadata support + action-based moves

- Added Battleship Fleet definition (carrier, battleship, cruiser, submarine, destroyer)
- Implemented action-based MovePayload (`action: "place" | "shoot"`)
- Added placement and shot validation (ValidatePlacementMove, ValidateShotMove)
- Added ApplyPlacement and ApplyShot with correct ship placement + hit/miss logic
- Added pX_placed, pX_ready tracking and phase switching (placement → battle)
- Added Metadata field to MatchState (for phase/ready tracking)
- Updated MatchInit to initialize placement phase and readiness flags
- Updated MatchLoop to enforce turn order only during battle phase
- Added debug logging for state broadcasts
- Fixed protobuf dependency marking as indirect

plugins/games/rules.go

@@ -6,7 +6,8 @@ import "localrepo/plugins/structs"
 // It is intentionally untyped (map[string]interface{}) so each game
 // can define its own move structure (e.g., row/col, coordinate, action type, etc.)
 type MovePayload struct {
-    Data map[string]interface{} `json:"data"`
+    Action string                 `json:"action"` // "place" or "shoot"
+    Data map[string]interface{}   `json:"data"`
 }
 
 // GameRules defines a generic interface for match logic.