fix(ligretto): preserve game state on resume

[memebattle-dev]

Summary

• add a dedicated shared websocket contract and separate frontend/backend path for resuming paused games
• resume by changing only GameStatus.Pause to GameStatus.InGame, preserving players, decks, cards, playground, spectators, and configuration
• restrict resume requests to the game host and ignore unknown games without broadcasting
• keep fresh-round start initialization separate and label the paused host action as Resume
• add backend controller, frontend listener, dispatch, and button-label regression coverage

Tests

• pnpm --filter @memebattle/ligretto-gameplay-backend test — 2 files, 17 tests passed
• pnpm --filter @memebattle/ligretto-gameplay-backend ts-check — passed
• pnpm test:ci && pnpm ts-check in apps/ligretto-frontend — 8 files, 58 tests passed; typecheck passed
• pnpm lint:check — passed
• pnpm fmt:check — passed
• root pnpm test:ci — passed across the workspace
• root pnpm ts-check — all Ligretto/shared projects passed; the command retains the existing failure in untouched apps/blog generated Next route/layout types where locale is widened to string
• independent staged-diff review — passed after adding host authorization and unknown-game guards

Risks

• resume is intentionally immediate and does not reuse the fresh-round countdown
• invalid lifecycle requests preserve state; unauthorized and unknown-game requests are ignored without broadcast

Fixes #643

[memebattle-dev]

Rebased this branch onto the current master and pushed commit 170520c to harden resume concurrency: host authorization and the paused-state transition are now atomic, rejected resumes do not broadcast, and successful resumes broadcast the freshest canonical game. Added deterministic regression coverage for stale-host and concurrent-update races. Local workspace tests, lint, and format checks passed; root typecheck retains only the pre-existing untouched apps/blog generated Next type errors. All PR checks are green.