fix(security): Phase 1 P0 hardening from cross-project audit

Close open uploads, image-proxy SSRF, fail-open AI quotas in production,
auth gaps on app routes, and MCP tenant isolation issues.

Co-authored-by: Cursor <cursoragent@cursor.com>

docker-compose.yml

@@ -127,7 +127,7 @@ services:
       - .env.docker
     ports:
       # SSE mode exposes port 3001, stdio mode doesn't need ports
-      - "3001:3001"
+      - "127.0.0.1:3001:3001"
     environment:
       # DATABASE_URL is auto-constructed from PostgreSQL credentials (not in .env.docker)
       - DATABASE_URL=postgresql://${POSTGRES_USER:-memento}:${POSTGRES_PASSWORD:-memento}@postgres:5432/${POSTGRES_DB:-memento}