v0.8.4: Documentation refresh + surface sizing fix

Docs pass covering v0.7.5–v0.8.3 module additions:
- STARLARK-REFERENCE: workspace module, permissions module, settings.has_capability()
- EXTENSION-GUIDE: capabilities manifest, vector(N) column, user_permissions,
  gate_permission, updated permissions list
- Tutorial reviewed for v0.7+ accuracy (no changes needed)

Surface sizing fix: .surface-inner converted to flex column layout so
the shell topbar and surface container share vertical space correctly.
All surface containers changed from height:100% to flex:1;min-height:0.
Eliminates 44px scroll cutoff on docs, admin, settings, and all
extension surfaces.

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

server/pages/templates/surfaces/team-admin.html

@@ -6,7 +6,7 @@
 
 {{define "surface-team-admin"}}
 <div id="shell-topbar"></div>
-<div id="team-admin-mount" class="surface-team-admin" style="height:100%;overflow:hidden;">
+<div id="team-admin-mount" class="surface-team-admin" style="flex:1;min-height:0;overflow:hidden;">
     <div class="settings-placeholder" style="padding:40px;text-align:center;">Loading team admin&hellip;</div>
 </div>
 {{end}}