feat: rename keep-notes to memento-note, migrate to PostgreSQL, fix MCP bugs

- Rename directory keep-notes -> memento-note with all code references
- Prisma: SQLite -> PostgreSQL (both app and MCP server schemas)
- Sync MCP schema with main app (add missing fields, relations, indexes)
- Delete 17 SQLite migrations (clean slate for PostgreSQL)
- Remove SQLite dependencies (@libsql/client, better-sqlite3, etc.)
- Fix MCP server: hardcoded Windows DB paths -> DATABASE_URL env var
- Fix MCP server: .dockerignore excluded index-sse.js (SSE mode broken)
- MCP Dockerfile: node:20 -> node:22
- Docker Compose: add postgres service, remove SQLite volume
- Generate favicon.ico, icon-192.png, icon-512.png, apple-icon.png
- Update layout.tsx icons and manifest.json for PNG icons
- Update all .env files for PostgreSQL
- Rewrite README.md with updated sections
- Remove mcp-server/node_modules and prisma/client-generated from git tracking

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

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

@@ -0,0 +1,83 @@
+'use server'
+
+import { auth } from '@/auth'
+import { prisma } from '@/lib/prisma'
+import { revalidatePath, revalidateTag } from 'next/cache'
+
+export type UserSettingsData = {
+  theme?: 'light' | 'dark' | 'auto' | 'sepia' | 'midnight' | 'blue'
+}
+
+/**
+ * Update user settings (theme, etc.)
+ */
+export async function updateUserSettings(settings: UserSettingsData) {
+
+  const session = await auth()
+
+  if (!session?.user?.id) {
+    console.error('[updateUserSettings] Unauthorized')
+    throw new Error('Unauthorized')
+  }
+
+  try {
+    const result = await prisma.user.update({
+      where: { id: session.user.id },
+      data: settings
+    })
+
+
+    revalidatePath('/', 'layout')
+    revalidateTag('user-settings')
+
+    return { success: true }
+  } catch (error) {
+    console.error('Error updating user settings:', error)
+    throw new Error('Failed to update user settings')
+  }
+}
+
+/**
+ * Get user settings for current user (Cached)
+ */
+import { unstable_cache } from 'next/cache'
+
+// Internal cached function
+const getCachedUserSettings = unstable_cache(
+  async (userId: string) => {
+    try {
+      const user = await prisma.user.findUnique({
+        where: { id: userId },
+        select: { theme: true }
+      })
+
+      return {
+        theme: (user?.theme || 'light') as 'light' | 'dark' | 'auto' | 'sepia' | 'midnight' | 'blue'
+      }
+    } catch (error) {
+      console.error('Error getting user settings:', error)
+      return {
+        theme: 'light' as const
+      }
+    }
+  },
+  ['user-settings'],
+  { tags: ['user-settings'] }
+)
+
+export async function getUserSettings(userId?: string) {
+  let id = userId
+
+  if (!id) {
+    const session = await auth()
+    id = session?.user?.id
+  }
+
+  if (!id) {
+    return {
+      theme: 'light' as const
+    }
+  }
+
+  return getCachedUserSettings(id)
+}