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/lib/ai/tools/note-crud.tool.ts

@@ -7,6 +7,7 @@ import { tool } from 'ai'
 import { z } from 'zod'
 import { toolRegistry } from './registry'
 import { prisma } from '@/lib/prisma'
+import { markdownToHtml } from '@/lib/markdown-to-html'
 
 // --- note_read ---
 toolRegistry.register({
@@ -50,11 +51,13 @@ toolRegistry.register({
       }),
       execute: async ({ title, content, notebookId, images }) => {
         try {
+          const htmlContent = markdownToHtml(content)
           const note = await prisma.note.create({
             data: {
               title,
-              content,
-              isMarkdown: true,
+              content: htmlContent,
+              type: 'richtext',
+              isMarkdown: false,
               autoGenerated: true,
               userId: ctx.userId,
               notebookId: notebookId || null,