Feat default surface routing + fix startup hang (#4)

Default surface routing (v0.2.1):
- `/` redirects to configurable default surface with fallback chain:
  configured → first enabled extension surface → /admin
- Auto-sets default_surface on first extension surface install
- Admin settings UI: Default Surface dropdown
- disabledRedirect() and extension surface disabled redirect now go to
  /admin instead of / to prevent redirect loops

Fix Gin route param conflict causing backend startup hang:
- Team package settings routes used `:pkgId` while sibling routes used
  `:id` — Gin's radix tree entered infinite loop on conflicting param
  names. Unified to `:id`.

Docker entrypoint hardening:
- Health check timeout 10s → 60s
- Stale backend process cleanup on restart
- Crash detection (exit early if backend dies)

Roadmap direction updates:
- v0.3.0: Notes surface (Obsidian-style) replaces Editor surface
- v0.4.0: MVP (was v0.5.0) — chat moved to post-MVP
- No built-in auto-install — explicit install only

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

CHANGELOG.md

@@ -2,7 +2,35 @@
 
 All notable changes to Switchboard Core are documented here.
 
-## [Unreleased] — v0.2.0
+## [Unreleased] — v0.2.1
+
+### Added
+
+- **Default surface routing**: `/` redirects to configurable default surface.
+  Fallback chain: configured default → first enabled extension surface → `/admin`.
+  First installed extension surface auto-becomes default. Admin can change via
+  Settings > Default Surface dropdown.
+- `default_surface` global config key (JSON `{"id": "slug"}`)
+- Admin settings UI: Default Surface dropdown (extension surfaces only)
+
+### Changed
+
+- `disabledRedirect()` now redirects to `/admin` instead of `/` to prevent
+  redirect loops when the default surface is disabled
+- Disabled extension surfaces (`/s/:slug`) redirect to `/admin` instead of `/`
+
+### Fixed
+
+- **Gin route param conflict** causing backend startup hang: team-scoped
+  package settings routes used `:pkgId` while sibling routes used `:id`.
+  Gin's radix tree entered an infinite loop on the conflicting param names.
+  Unified to `:id` across all `/teams/:teamId/packages/` routes.
+- Docker entrypoint: increased health check timeout (10s → 60s), added stale
+  process cleanup and crash detection to prevent zombie backends on restart
+
+---
+
+## [v0.2.0] — 2026-03-26
 
 ### Added