#148 Harden Metal presentation lifetimes

Fixes verified replay completion safety. Adds renderer lifetime invalidation, generation-based stale-frame rejection, and moves synchronous callback delivery outside the draw mutex while preserving current swap-chain drain and iOS queued behavior.\n\nVerified: zig build test -Drenderer=metal passes.

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Summary by cubic

Hardens Metal presentation lifetimes to prevent stale or late GPU completions from mutating UI or renderer state after resize or teardown. Adds generation-based validation and moves sync presentation callback delivery outside the draw mutex while preserving swap-chain drain and iOS’s queued behavior.

• Bug Fixes
  • Generation-tracked IOSurfaceLayer lifetime rejects stale frames and cancels after teardown.
  • Surface size is clamped and observed; presentation_generation is passed through frame/present paths.
  • setSurfaceSync validates generation and size; returns false instead of touching invalid state.
  • Sync presentation returns the callback to the caller; delivery occurs after draw_mutex unlocks (async and iOS unchanged).
  • Added tests for lifetime invalidation and stale-generation rejection.

Summary by CodeRabbit

• Bug Fixes
  • Improved Metal presentation reliability by preventing stale or invalid frame updates from reaching the display.
  • Prevented queued presentation callbacks from affecting detached or inactive surfaces.
  • Added safeguards to reject surfaces whose dimensions do not match the current drawable area.
  • Clamped runtime surface sizes to supported device texture limits.
  • Improved synchronization for frame completion and presentation updates to reduce visual glitches during resizing or rapid frame changes.