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/handlers/admin.go

@@ -361,47 +361,15 @@ func (h *AdminHandler) PublicSettings(c *gin.Context) {
 	// Banner config, branding, etc. — safe subset for non-admin users
 	banner, _ := h.stores.GlobalConfig.Get(c.Request.Context(), "banner")
 	branding, _ := h.stores.GlobalConfig.Get(c.Request.Context(), "branding")
-	systemPrompt, _ := h.stores.GlobalConfig.Get(c.Request.Context(), "system_prompt")
 	policies, _ := h.stores.Policies.GetAll(c.Request.Context())
 
-	// Paste-to-file threshold (admin-configurable via storage.paste_to_file_chars, default 2000)
-	pasteChars := 2000
-	if storageSettings, err := h.stores.GlobalConfig.Get(c.Request.Context(), "storage"); err == nil {
-		if v, ok := storageSettings["paste_to_file_chars"]; ok {
-			switch n := v.(type) {
-			case float64:
-				pasteChars = int(n)
-			case int:
-				pasteChars = n
-			}
-		}
-	}
-
-	// Only tell the user whether admin prompt exists — don't expose content
-	hasAdminPrompt := false
-	if content, ok := systemPrompt["content"].(string); ok && content != "" {
-		hasAdminPrompt = true
-	}
-
-	// Retention TTL (v0.37.14 — days before purge for global/team channels)
-	retentionTTL := 0
-	if ttlCfg, err := h.stores.GlobalConfig.Get(c.Request.Context(), "retention_ttl_days"); err == nil {
-		if v, ok := ttlCfg["value"].(float64); ok {
-			retentionTTL = int(v)
-		}
-	}
-
 	c.JSON(http.StatusOK, gin.H{
-		"banner":              banner,
-		"branding":            branding,
-		"has_admin_prompt":    hasAdminPrompt,
-		"storage_configured":  storageConfigured,
-		"paste_to_file_chars": pasteChars,
+		"banner":             banner,
+		"branding":           branding,
+		"storage_configured": storageConfigured,
 		"policies": gin.H{
-			"allow_registration":      policies["allow_registration"],
-			"allow_user_byok":         policies["allow_user_byok"],
-			"allow_user_personas":     policies["allow_user_personas"],
-			"retention_ttl_days":      retentionTTL,
+			"allow_registration": policies["allow_registration"],
+			"allow_user_byok":    policies["allow_user_byok"],
 		},
 	})
 }