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/api/ai/echo/route.ts

@@ -0,0 +1,92 @@
+import { NextRequest, NextResponse } from 'next/server'
+import { auth } from '@/auth'
+import { memoryEchoService } from '@/lib/ai/services/memory-echo.service'
+
+/**
+ * GET /api/ai/echo
+ * Fetch next Memory Echo insight for current user
+ */
+export async function GET(req: NextRequest) {
+  try {
+    const session = await auth()
+
+    if (!session?.user?.id) {
+      return NextResponse.json(
+        { error: 'Unauthorized' },
+        { status: 401 }
+      )
+    }
+
+    // Get next insight (respects frequency limits)
+    const insight = await memoryEchoService.getNextInsight(session.user.id)
+
+    if (!insight) {
+      return NextResponse.json(
+        {
+          insight: null,
+          message: 'No new insights available at the moment. Memory Echo will notify you when we discover connections between your notes.'
+        }
+      )
+    }
+
+    return NextResponse.json({ insight })
+
+  } catch (error) {
+    return NextResponse.json(
+      { error: 'Failed to fetch Memory Echo insight' },
+      { status: 500 }
+    )
+  }
+}
+
+/**
+ * POST /api/ai/echo
+ * Submit feedback or mark as viewed
+ */
+export async function POST(req: NextRequest) {
+  try {
+    const session = await auth()
+
+    if (!session?.user?.id) {
+      return NextResponse.json(
+        { error: 'Unauthorized' },
+        { status: 401 }
+      )
+    }
+
+    const body = await req.json()
+    const { action, insightId, feedback } = body
+
+    if (action === 'view') {
+      // Mark insight as viewed
+      await memoryEchoService.markAsViewed(insightId)
+
+      return NextResponse.json({ success: true })
+
+    } else if (action === 'feedback') {
+      // Submit feedback (thumbs_up or thumbs_down)
+      if (!feedback || !['thumbs_up', 'thumbs_down'].includes(feedback)) {
+        return NextResponse.json(
+          { error: 'Invalid feedback. Must be thumbs_up or thumbs_down' },
+          { status: 400 }
+        )
+      }
+
+      await memoryEchoService.submitFeedback(insightId, feedback)
+
+      return NextResponse.json({ success: true })
+
+    } else {
+      return NextResponse.json(
+        { error: 'Invalid action. Must be "view" or "feedback"' },
+        { status: 400 }
+      )
+    }
+
+  } catch (error) {
+    return NextResponse.json(
+      { error: 'Failed to process request' },
+      { status: 500 }
+    )
+  }
+}