Feat v0.2.6 admin settings audit (#10)

Roadmap reorder: Extension Lifecycle moved to v0.3.x, settings audit
milestones renumbered (v0.2.7→v0.2.6, v0.2.8→v0.2.7, v0.2.9→v0.2.8).
Added v0.2.9 for builtin extension retirement — 6 chat-centric
extensions (csv-table, diff-viewer, js-sandbox, katex, mermaid, regex)
are dormant until a chat surface ships; roadmap tracks converting them
to regular packages and removing the auto-seed mechanism.

Admin settings E2E verified — all 7 sections (default surface,
registration, banner, message bar, footer, vault, email) render and
save correctly. Packages surface verified (17/17 loaded).

Dead code removed:
- sectionCategory(): AI/routing/channel cases, default→system
- PublicSettings(): system_prompt, retention_ttl, paste_to_file,
  allow_user_personas
- PolicyDefaults: allow_raw_model_access, default_model
- Profile handlers: allow_raw_model_access, kb_direct_access lookups
- Test seeds: model_roles setting, allow_raw_model_access policy
- packages.js: 'chat' from CORE_IDS

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

server/pages/loaders.go

@@ -79,16 +79,14 @@ func sectionCategory(section string) string {
 	switch section {
 	case "users", "teams", "groups":
 		return "people"
-	case "providers", "models", "personas", "roles", "knowledgeBases", "memory":
-		return "ai"
-	case "health", "routing", "capabilities":
-		return "routing"
-	case "settings", "storage", "packages", "channels", "broadcast":
+	case "workflows":
+		return "workflows"
+	case "settings", "storage", "packages", "broadcast":
 		return "system"
 	case "usage", "audit", "stats":
 		return "monitoring"
 	default:
-		return "ai" // default landing
+		return "system"
 	}
 }