v0.3.2 - Optional game timer

What's changed

• Added an optional elapsed game timer.
• Timer starts on the first move, stops when the match ends, and resets with the board.
• Recent completed match summaries now include duration for timed games.
• Updated README, roadmap, accessibility notes, changelog, and package metadata.

Verification

• Node syntax checks passed for src/engine.js and src/main.js.
• Node test suite passed: 14 tests.
• Local browser smoke checks passed for timer behavior and mobile layout.
• GitHub Actions CI and Pages deployment passed.
• Live GitHub Pages timer smoke check passed.