Feat v0.6.1-v0.6.2: backup/restore, docs surface, dynamic OpenAPI

v0.6.1 — Backup tooling (.swb ZIP export/import), admin backup section,
docs surface with markdown rendering, 5 reference docs, 6 handler tests.

v0.6.2 — Dark mode contrast fixes, topbar nav, 📖 docs icon, dynamic
OpenAPI spec with extension route merging, docs outline sidebar,
scroll/routing fixes; 7 new tests.

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

server/pages/templates/base.html

@@ -89,6 +89,7 @@
         {{else if eq .Surface "team-admin"}}{{template "surface-team-admin" .}}
         {{else if eq .Surface "settings"}}{{template "surface-settings" .}}
         {{else if eq .Surface "welcome"}}{{template "surface-welcome" .}}
+        {{else if eq .Surface "docs"}}{{template "surface-docs" .}}
         {{else if and .Manifest (eq .Manifest.Source "extension")}}{{template "surface-extension" .}}
         {{else}}<div style="padding:20px">Unknown surface: {{.Surface}}</div>
         {{end}}
@@ -124,6 +125,7 @@
     {{if eq .Surface "team-admin"}}{{template "scripts-team-admin" .}}{{end}}
     {{if eq .Surface "settings"}}{{template "scripts-settings" .}}{{end}}
     {{if eq .Surface "welcome"}}{{template "scripts-welcome" .}}{{end}}
+    {{if eq .Surface "docs"}}{{template "scripts-docs" .}}{{end}}
     {{/* v0.27.0: Extension surface JS — load Preact globals, boot SDK, then extension */}}
     {{if and .Manifest (eq .Manifest.Source "extension")}}
     <script type="module" nonce="{{.CSPNonce}}">