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>

app/api/extensions/ext/[...path]/route.ts

@@ -3,7 +3,6 @@ import { NextResponse } from 'next/server'
 import { ensureInitialized } from '@/lib/init'
 import { extensionRegistry } from '@/lib/extensions/registry'
 import { createExtensionContext } from '@/lib/extensions/context-factory'
-import { isExtensionEnabled } from '@/lib/extensions/toggle-check'
 import { hasAiConsent, isAiExtension } from '@/lib/extensions/ai-consent'
 import type { ApiRouteDefinition } from '@/lib/extensions/types'
 
@@ -118,13 +117,6 @@ async function handleRequest(
     return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
   }
 
-  // Toggle check — use extension's declared sector, fallback to 'general'
-  const sector = extension.sector || 'general'
-  const enabled = await isExtensionEnabled(user.id, sector, extensionId)
-  if (!enabled) {
-    return NextResponse.json({ error: 'Extension is disabled' }, { status: 403 })
-  }
-
   // AI consent check
   if (isAiExtension(extensionId)) {
     const consented = await hasAiConsent(supabase, user.id, extensionId)