Fix build issues found during Docker validation

- Dockerfile: add COPY db/ /app/db/ so migrations are available at
  runtime (server/src/db.js requires ../../db/migrations at startup)
- vite.config.js: fix dev proxy port from 3001 to 3000 to match
  server's default PORT

Docker build passes; server starts and connects to DB correctly.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.claude/settings.local.json

@@ -13,7 +13,12 @@
       "Bash(td review:*)",
       "Bash(td approve:*)",
       "Bash(td complete:*)",
-      "Bash(td update:*)"
+      "Bash(td update:*)",
+      "Bash(npm --version)",
+      "Bash(docker --version)",
+      "Bash(docker compose:*)",
+      "Bash(docker build:*)",
+      "Bash(docker run:*)"
     ]
   }
 }