feat: 8 AI providers, rich text editor, agent notifications, UI contrast & font settings

- Add DeepSeek, OpenRouter, Mistral, Z.AI, LM Studio as AI providers
  with editable model names via Combobox in admin settings
- Fix OpenRouter broken by normalizeProvider bug in config.ts
- Convert agent-created notes from Markdown to HTML (TipTap rich text)
- Add Notification model + in-app notifications for agent results
- Agent notification click opens the created note directly
- Add note count display on notebook and inbox headers
- Fix checklist toggle in card view (persist state via localCheckItems)
- Add checklist creation option in tabs/list view (dropdown on + button)
- Fix image description ENOENT error with HTTP fallback
- Improve UI contrast across all themes (input, border, checkbox visibility)
- Add font family setting (Inter vs System Default) in Appearance settings
- Fix CSS font-sans variable conflict (removed dead Geist references)
- Update README with new features and 8 providers

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

memento-note/app/actions/admin-settings.ts

@@ -3,7 +3,6 @@
 import prisma from '@/lib/prisma'
 import { auth } from '@/auth'
 import { sendEmail } from '@/lib/mail'
-import { updateTag } from 'next/cache'
 
 async function checkAdmin() {
   const session = await auth()
@@ -62,9 +61,6 @@ export async function updateSystemConfig(data: Record<string, string>) {
 
     await prisma.$transaction(operations)
 
-    // Invalidate cache after update
-    updateTag('system-config')
-
     return { success: true }
   } catch (error) {
     console.error('Failed to update settings:', error)