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/1.9.5.md

@@ -0,0 +1,36 @@
+---
+version: 1.9.5
+date: 2026-04-14
+---
+
+## App
+
+### New
+- Security/Auth: added passkey sign-in for protected instances and new 1-week/30-day session expiration options (thanks to @daveotero, @pm0u).
+- Voice: added OpenAI-compatible custom server support for both text-to-speech and speech-to-text, including configurable TTS model/pitch/volume and stricter custom URL validation for safer setup (thanks to @ablepharus).
+
+### Improvements
+- Sync/Performance: optimized multi-session streaming with per-directory queues, event coalescing, and parts-gap recovery to keep live updates smooth under heavy activity (thanks to @jwcrystal).
+- Sessions/UI: kept active sessions visible in Recent, auto-expanded parent groups when opening subagent sessions, and hid empty archived/folder sections (thanks to @jwcrystal).
+
+### Fixes
+- Chat/Tool Output: added an interactive tree viewer for structured outputs and fixed JSON quote rendering (thanks to @yaozhenghangma).
+- Chat/Reliability: fixed question-tool content disappearing after refresh and hardened subagent/session recovery paths.
+- Git/UI: restored Git changes panel visibility and sidebar sync (thanks to @jwcrystal).
+- Desktop/Startup: delivered a more guided first-launch and smart recovery flow, plus startup and remote-window interaction fixes to reduce early-session friction (thanks to @jwcrystal).
+- Usage: added Zhipu AI Coding Plan tracking and restored model-variant compatibility with older OpenCode runtimes (thanks to @cainiao1992, @Chi-square-test).
+
+## VS Code
+
+### New
+- Usage: added Zhipu AI Coding Plan tracking (thanks to @cainiao1992).
+
+### Improvements
+- Sync/Performance: optimized multi-session streaming with per-directory queues, event coalescing, and parts-gap recovery for steady live updates in busy workspaces (thanks to @jwcrystal).
+- Task/Reliability: hardened subagent session resolution and polling lifecycle handling to reduce silent task failures (thanks to @jwcrystal).
+- Sessions/UI: kept active sessions visible in Recent, auto-expanded parent groups for subagent sessions, and hid empty archived/folder sections (thanks to @jwcrystal).
+
+### Fixes
+- Chat/Tool Output: added an interactive tree viewer for structured outputs and fixed JSON quote rendering (thanks to @yaozhenghangma).
+- Chat/Reliability: fixed question-tool content disappearing after refresh (thanks to @jwcrystal).
+- Models: restored model-variant compatibility with newer OpenCode runtimes (thanks to @Chi-square-test).