refactor: remove extension toggle system — compiled-in extensions are always active (#59)

The runtime toggle system (extension_toggles table, API routes, hooks, UI components)
added unnecessary complexity. Extensions controlled via extensions.config.json at build
time are now always active for all users. This removes ~835 lines of toggle-related code
including API routes, DB queries, the ExtensionToggleButton component, useEnabledExtensions
and useExtensionToggle hooks, and the toggle-check module. AI consent gating remains
unchanged.

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

lib/extensions/types.ts

@@ -52,17 +52,6 @@ export interface Sector {
   extensions: ExtensionDefinition[]
 }
 
-/** Database row for extension toggle state */
-export interface ExtensionToggle {
-  id: string
-  user_id: string
-  sector_slug: string
-  extension_slug: string
-  enabled: boolean
-  created_at: string
-  updated_at: string
-}
-
 // ============================================================
 // Extension Interface & Supporting Types
 // ============================================================