### Core Engine
- Updated `GameRules.ApplyMove` to return `(changed, gameOver, winnerIdx, keepTurn)`
- Added keepTurn handling in `MatchLoop` to support Battleship mode B (classic rules)
- Removed old single-board handling from MatchState and MatchInit
- Cleaned go.mod by marking protobuf dependency as indirect
### Battleship
- Implemented board-based state tracking using MatchState.Boards:
- `p0_ships`, `p0_shots`, `p1_ships`, `p1_shots`
- Removed legacy metadata-based ship/shot board encoding
- Rewrote ValidateMove to use structured boards
- Rewrote ApplyMove for classic Battleship rules (mode B):
- Hits allow the attacker to keep their turn
- Miss switches turn
- Destroyed ship sections marked `X`
- Improved CheckGameOver using structured boards
### TicTacToe
- Updated ApplyMove signature to match new interface
- Ensured TicTacToe always returns `keepTurn = false`
- Updated code paths to use MatchState.Boards instead of Board
### Summary
This commit completes the migration from a single-board architecture to a
multi-board architecture across the engine, TicTacToe, and Battleship, enabling
support for more complex games and multiple modes such as Battleship Mode B.
### Major changes
- Replace single-board MatchState (`Board`) with multi-board map (`Boards`)
- Update GenericMatch to initialize empty Boards and populate them via GameRules.InitBoards
- Remove legacy `newEmptyBoard` helper from match.go
- Update .gitignore to include *BKP* patterns
### GameRules interface
- Add InitBoards(players, cfg) to allow games to construct their own board sets
- Add detailed documentation explaining method responsibilities and usage
- Improve MovePayload comment clarity
### TicTacToe updates
- Implement InitBoards to produce a single `"tictactoe"` board
- Replace all old references to `state.Board` with `state.Boards["tictactoe"]`
- Make CheckGameOver, ValidateMove, and ApplyMove multi-board compatible
### Battleship updates
- Implement InitBoards generating per-player ships + shots boards:
- p0_ships, p0_shots
- p1_ships, p1_shots
### Match flow updates
- Boards are now created only when all players have joined
- Initial state broadcast now includes `boards` instead of `board`
This completes the backend migration for multi-board games and prepares the architecture
for Battleship and other complex board-based games.
Updated TicTacToeRules and BattleshipRules to implement ApplyMove(state, playerIdx, payload) (bool, bool, int) as required by GameRules.
Added win/draw resolution logic directly inside each game’s ApplyMove return.
Removed obsolete convertToGamePlayers helper.
Updated GenericMatch to call AssignPlayerSymbols with []*structs.Player directly.
Ensured all rule implementations now fully satisfy the GameRules interface.
### Highlights
- Introduced generic match engine (`generic_match.go`) implementing dynamic GameRules-based runtime.
- Added modular structure under `/plugins`:
- /plugins/game → GameRules interface + TicTacToe + Battleship rule sets
- /plugins/structs → Board, Player, MatchState generic structs
- /plugins/modules → matchmaking + RPC handlers + match engine
- Migrated TicTacToe logic into reusable rule implementation.
- Added Battleship game support using same engine.
- Updated matchmaking to accept { game, mode } for multi-game routing.
- Updated UI contract: clients must send `game` (and optional `mode`) when joining matchmaking.
- Removed hardcoded TicTacToe match registration.
- Registered a single “generic” authoritative match with ruleset registry.
- Normalized imports under local dev module path.
- Ensured MatchState and Board are now generic and reusable across games.
- Added strict requirement for `game` metadata in match flow (error if missing).
- Cleaned initial state creation into MatchInit with flexible board dimensions.
- Improved MatchLeave for proper forfeit handling through GameRules.
### Result
The server now supports an unlimited number of turn-based board games
via swappable rulesets while keeping a single authoritative Nakama match loop.
