feat: remove ai-chat extension from hosted version, move chat widget to bottom-right

Remove ai-chat from extensions.config.json and docker/extensions.hosted.json
(kept in self-hosted config). Remove ChatWidget imports from dashboard layout
and root page. Reposition chat widget FAB and panel to bottom-right corner.
Regenerate extension registry.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/extensions/_generated/extension-list.ts

@@ -1,11 +1,9 @@
 // AUTO-GENERATED — do not edit. Run `npm run setup:extensions` to regenerate.
 import type { Extension } from '../types'
 import { enableBankingExtension } from '@/extensions/general/enable-banking'
-import { aiChatExtension } from '@/extensions/general/ai-chat'
 import { emailExtension } from '@/extensions/general/email'
 
 export const FIRST_PARTY_EXTENSIONS: Extension[] = [
   enableBankingExtension,
-  aiChatExtension,
   emailExtension,
 ]