feat(changelog): one source file per release, generated outputs

Release notes now live in changelog/<version>.md (front matter with
version and date, then ## App and ## VS Code sections grouped into
New, Improvements, Fixes, Misc) plus changelog/unreleased.md for what
has not shipped. `bun run changelog:build` renders CHANGELOG.md,
packages/vscode/CHANGELOG.md, and changelog/index.json from them;
`changelog:check` fails when the outputs are behind and runs in CI and
in release:prepare. `oc-dev create-release` promotes unreleased.md to
the versioned file dated today and rebuilds.

The existing history was split mechanically: every bullet kept, sorted
into groups by keyword, five hand-typed headers with one-digit days
normalised to YYYY-MM-DD (the update dialog matched none of them). The
generated files keep today's release headers, which the update dialog,
the release workflow, and the website match by regex.

Claude-Session: https://claude.ai/code/session_01VqV56Hez25hTxXH4ipJfzH

changelog/1.22.0.md

@@ -0,0 +1,34 @@
+---
+version: 1.22.0
+date: 2026-08-30
+---
+
+## App
+
+### New
+- **Git:** projects containing several repositories can now switch between them from the Git tab. Diff, pull request, walkthrough, mobile Changes, and work status follow the selected repository (thanks to @jaygupta17).
+
+### Improvements
+- **Linear integration:** connect a workspace in Settings → Integrations, browse and filter issues, and start a session or worktree from an issue. OpenChamber reports session progress back to Linear and can attach an issue to the next chat message (thanks to @AlexKutas).
+- **Voice:** local text-to-speech and macOS say now choose a voice that matches the reply's language. Additional local models download on first use, and the voice picker lists voices from every installed model.
+- Files: Ctrl/Cmd+F opens search in the Markdown preview even when the preview is not focused.
+- GitHub: account connection has moved to Settings → Integrations. The pull-request panel includes account controls, and its context-rail icon appears only when connected.
+- Settings: themes are now remembered per OpenChamber instance, so windows connected to different instances keep their own theme (thanks to @kydorn).
+- Scheduled tasks: Goal, Auto-accept, and other task settings are preserved when older OpenChamber builds share the same project config.
+- Desktop: on Windows and Linux, the close button reaches the top-right corner and follows the theme on hover (thanks to @kydorn).
+
+### Fixes
+- **Chat:** sessions opened from the sidebar stay at the latest message, and switching sessions no longer causes jumps, partial rendering, crossfades, or tab-title shifts.
+- Chat: command, skill, and file autocomplete in projectless chats no longer uses the previously selected project.
+- Chat: reverting to a message, or forking from one, now brings its attached context back to the composer — review comments, chat and file quotes, terminal selections, and browser annotations are no longer lost.
+- Chat: stopped and unanswered turns now explain what happened. The status report includes recent session, send, and managed OpenCode errors, plus log locations.
+- Git: the commit graph no longer leaves a lane gap when the same branch is merged twice (thanks to @Naputt1).
+
+## VS Code
+
+### Improvements
+- Chat: a session opened from the sidebar lands at its end and stays there, instead of landing above the bottom or snapping up a moment later.
+
+### Fixes
+- Switching sessions is now visually stable, without conversation jumps or partial rendering.
+- Chat: a turn that OpenCode stopped no longer ends with nothing on screen — what OpenCode reported shows under the last message, and a message an idle session has left unanswered is named as such. The status report (Ctrl/Cmd+Shift+L) now lists the last session errors and rejected sends.