docs: v0.6.3 changelog and roadmap update

Mark all v0.6.3 roadmap items done, add changelog section.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -2,6 +2,45 @@
 
 All notable changes to Switchboard Core are documented here.
 
+## v0.6.3 — Dead Code Sweep + Registry Fix
+
+Pre-fork hardening: fix broken registry install, add registry settings UI,
+clean up dead code, narrow default bundle.
+
+### Fixed
+
+- **Registry install**: SDK was sending `{ url }` but the Go handler expects
+  `{ download_url }`, causing every registry Install click to return 400.
+
+### Added
+
+- **Package Registry settings**: New "Package Registry" section in Admin >
+  Settings with a URL input field for configuring the external registry.
+- **`scripts/generate-registry.sh`**: Shell script that reads `.pkg` ZIPs,
+  extracts manifests, and emits a `registry.json` for self-hosted discovery.
+- **`docs/PACKAGE-REGISTRY.md`**: Documents registry JSON format, admin
+  configuration, script usage, and self-hosting setup.
+
+### Removed
+
+- **Dead Go code**: Orphaned channel/message type comments from
+  `interfaces.go`, unused `roleFilterType()` from `pages.go`, stale version
+  comment from `main.go`.
+- **Dead vendor JS**: `marked.min.js` (40KB) and `purify.min.js` (22KB) —
+  unused vendor copies with zero production imports. Removed cache entries
+  from `sw.js`.
+- **`dev.html`**: 676-line standalone dev gallery, not referenced by anything.
+- **Pre-fork version comments**: Stripped `// v0.X.X:` annotations from 72
+  files. Config-doc version references (compatibility requirements) preserved.
+
+### Changed
+
+- **Default bundle narrowed** from 10 packages to 5: `notes`, `chat`,
+  `chat-core`, `mermaid-renderer`, `schedules`. All other packages remain
+  available via `BUNDLED_PACKAGES=*` or explicit list.
+
+---
+
 ## v0.6.2 — Docs Polish + Dynamic OpenAPI
 
 Docs surface polish and dynamic OpenAPI spec with extension route merging.