Release v0.64.0

What's Changed

• refactor(a2a-server): implement V1 to V2 settings migration logic by @jvargassanchez-dot in #29450
• fix(acp): bridge PromptResponse.usage and emit usage_update notifications (#29389) by @elberthc-byte in #29549
• Changelog for v0.63.0-preview.0 by @gemini-cli-robot in #29565
• fix(cli): propagate resolved folder trust state in headless mode (#29031) by @amelidev in #29528
• chore(release): bump version to 0.64.0-nightly.20260929.gd75234cae by @gemini-cli-robot in #29567
• fix(cli): prevent CPU hang and quote swallowing on @ within code (#29434) by @elberthc-byte in #29557
• fix(core): serialize file tool operations and make writes atomic (#29078) by @elberthc-byte in #29499
• fix(core): implement append-only delta patching and bounded history windowing in ChatRecordingService by @jvargassanchez-dot in #29568
• fix(cli): persist state atomically and recover from backup on corruption by @urielefrenvirtusa in #29558
• fix(cli): ensure Ctrl+C emergency abort reaches cancellation handler during active operations by @urielefrenvirtusa in #29586
• fix(cli): resolve @file:line references and prevent ghost text wrap hang by @jesussamuel-byte in #29581
• fix(ui): ensure Windows ConPTY forwards IME cursor position by @jesussamuel-byte in #29560
• fix(cli): retry directory removal on Windows locking errors during extension updates by @jesussamuel-byte in #29540
• fix(acp): resolve session by exact id and handle listener cleanup on session failure by @diegogodinezr in #29580
• fix(cli): preserve scroll position and partition pending height budget by @luisfelipe-alt in #29520
• fix(cli): ensure Enter and Spacebar reliably confirm selection list options by @ugorla-dev in #29502
• fix(patch): cherry-pick 2ce1a69 to release/v0.64.0-preview.0-pr-29672 to patch version v0.64.0-preview.0 and create version 0.64.0-preview.1 by @gemini-cli-robot in #29696

Full Changelog: v0.63.0...v0.64.0