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/services/image-description.service.ts

@@ -19,23 +19,43 @@ export interface ImageDescriptionResult {
 
 const UPLOAD_DIR = path.join(process.cwd(), 'data', 'uploads')
 
-async function resolveImageAsBase64(imageUrl: string): Promise<string> {
+async function resolveImageAsBase64(imageUrl: string): Promise<string | null> {
   const localMatch = imageUrl.match(/\/uploads\/(.+)/)
   if (localMatch) {
-    const filePath = path.join(UPLOAD_DIR, localMatch[1])
-    const buffer = await readFile(filePath)
-    const ext = path.extname(imageUrl).toLowerCase()
-    const mime = ext === '.png' ? 'image/png' : ext === '.gif' ? 'image/gif' : ext === '.webp' ? 'image/webp' : 'image/jpeg'
-    return `data:${mime};base64,${buffer.toString('base64')}`
+    // Try reading from filesystem first
+    try {
+      const filePath = path.join(UPLOAD_DIR, localMatch[1])
+      const buffer = await readFile(filePath)
+      const ext = path.extname(imageUrl).toLowerCase()
+      const mime = ext === '.png' ? 'image/png' : ext === '.gif' ? 'image/gif' : ext === '.webp' ? 'image/webp' : 'image/jpeg'
+      return `data:${mime};base64,${buffer.toString('base64')}`
+    } catch {
+      // File not on disk — fallback to internal HTTP API (same path the browser uses)
+      try {
+        const baseUrl = process.env.NEXTAUTH_URL || process.env.NEXT_PUBLIC_APP_URL || 'http://localhost:3000'
+        const res = await fetch(`${baseUrl}${imageUrl}`)
+        if (!res.ok) return null
+        const contentType = res.headers.get('content-type') || 'image/jpeg'
+        const arrayBuffer = await res.arrayBuffer()
+        const base64 = Buffer.from(arrayBuffer).toString('base64')
+        return `data:${contentType};base64,${base64}`
+      } catch {
+        return null
+      }
+    }
   }
 
   // Remote URL — fetch and convert
-  const res = await fetch(imageUrl)
-  if (!res.ok) throw new Error(`Failed to fetch image: ${imageUrl}`)
-  const contentType = res.headers.get('content-type') || 'image/jpeg'
-  const arrayBuffer = await res.arrayBuffer()
-  const base64 = Buffer.from(arrayBuffer).toString('base64')
-  return `data:${contentType};base64,${base64}`
+  try {
+    const res = await fetch(imageUrl)
+    if (!res.ok) return null
+    const contentType = res.headers.get('content-type') || 'image/jpeg'
+    const arrayBuffer = await res.arrayBuffer()
+    const base64 = Buffer.from(arrayBuffer).toString('base64')
+    return `data:${contentType};base64,${base64}`
+  } catch {
+    return null
+  }
 }
 
 export async function describeImages(
@@ -55,8 +75,9 @@ export async function describeImages(
   }
   const langName = langMap[language] || 'English'
 
-  // Resolve all images as base64 data URLs (same approach as the chat route)
-  const imageDataUrls = await Promise.all(imageUrls.map(url => resolveImageAsBase64(url)))
+  // Resolve all images as base64 data URLs — skip any that can't be found
+  const resolved = await Promise.all(imageUrls.map(url => resolveImageAsBase64(url)))
+  const imageDataUrls = resolved.filter((d): d is string => d !== null)
 
   if (isTitleMode) {
     const prompt = imageUrls.length === 1