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/1.6.7.md

@@ -0,0 +1,30 @@
+---
+version: 1.6.7
+date: 2026-02-10
+---
+
+## App
+
+### New
+- Voice: added built-in voice input and read-aloud responses with multiple providers (thanks to @gsxdsm).
+- Git: added multi-remote push selection and smarter fork-aware pull request creation to reduce manual branch/remote setup (thanks to @gsxdsm).
+- Usage: added usage pace and prediction indicators in the header and settings (thanks to @gsxdsm).
+- Desktop: added multi-window support with a dedicated "New Window" action for parallel work across projects (thanks to @yulia-ivashko).
+
+### Improvements
+- UI: refreshed header and settings layout, improved host switching, and upgraded the editor for smooth day-to-day navigation and editing.
+
+### Fixes
+- Diff/Plans: fixed comment draft collisions and improved multi-line comment editing in plan and file workflows (thanks to @nelsonPires5).
+- Notifications: stopped firing completion notifications for comment draft edits to reduce noisy alerts during review-heavy sessions (thanks to @nelsonPires5).
+- Settings: added confirmation dialogs for destructive delete/reset actions to prevent accidental data loss.
+- Reliability: fixed message loading edge cases, stabilized voice-mode persistence across restarts, and improved update flow behavior across platforms.
+
+## VS Code
+
+### New
+- Added usage pace and prediction indicators in the header and settings to make quota usage trends easier to track (thanks to @gsxdsm).
+- Added confirmation dialogs for destructive delete/reset actions to reduce accidental mistakes in settings and management flows.
+
+### Improvements
+- Improved reliability for message loading.