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/ai-settings.ts

@@ -23,6 +23,7 @@ export type UserAISettingsData = {
   autoLabeling?: boolean
   noteHistory?: boolean
   noteHistoryMode?: 'manual' | 'auto'
+  fontFamily?: 'inter' | 'system'
 }
 
 /** Only fields that exist on `UserAISettings` in Prisma (excludes e.g. `theme`, which lives on `User`). */
@@ -45,6 +46,7 @@ const USER_AI_SETTINGS_PRISMA_KEYS = [
   'autoLabeling',
   'noteHistory',
   'noteHistoryMode',
+  'fontFamily',
 ] as const
 
 type UserAISettingsPrismaKey = (typeof USER_AI_SETTINGS_PRISMA_KEYS)[number]
@@ -157,6 +159,7 @@ const getCachedAISettings = unstable_cache(
           autoLabeling: true,
           noteHistory: false,
           noteHistoryMode: 'manual' as const,
+          fontFamily: 'inter' as const,
         }
       }
 
@@ -188,6 +191,7 @@ const getCachedAISettings = unstable_cache(
         autoLabeling: settings.autoLabeling ?? true,
         noteHistory: settings.noteHistory ?? false,
         noteHistoryMode: (settings.noteHistoryMode ?? 'manual') as 'manual' | 'auto',
+        fontFamily: (settings.fontFamily || 'inter') as 'inter' | 'system',
       }
     } catch (error) {
       console.error('Error getting AI settings:', error)
@@ -212,6 +216,7 @@ const getCachedAISettings = unstable_cache(
         autoLabeling: true,
         noteHistory: false,
         noteHistoryMode: 'manual' as const,
+        fontFamily: 'inter' as const,
       }
     }
   },
@@ -249,6 +254,7 @@ export async function getAISettings(userId?: string) {
       autoLabeling: true,
       noteHistory: false,
       noteHistoryMode: 'manual' as const,
+      fontFamily: 'inter' as const,
     }
   }