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/auth.ts

@@ -0,0 +1,29 @@
+'use server';
+
+import { signIn } from '@/auth';
+import { AuthError } from 'next-auth';
+
+export async function authenticate(
+  prevState: string | undefined,
+  formData: FormData,
+) {
+  try {
+    await signIn('credentials', {
+      email: formData.get('email'),
+      password: formData.get('password'),
+      redirectTo: '/',
+    });
+  } catch (error) {
+    if (error instanceof AuthError) {
+      console.error('AuthError details:', error.type, error.message);
+      switch (error.type) {
+        case 'CredentialsSignin':
+          return 'Invalid credentials.';
+        default:
+          return `Auth error: ${error.type}`;
+      }
+    }
+    // IMPORTANT: Next.js redirects throw a special error that must be rethrown
+    throw error;
+  }
+}