fix: bind deepagents streaming frontend to loopback

[kic635]

Summary

• Bind the DeepAgents streaming Vite dev server explicitly to 127.0.0.1.
• Add a generated-project regression test matching the lifecycle frontend health-check address.

Verification

• Rendered the template successfully.
• Frontend Vitest: 3 test files, 5 tests passed.
• Frontend Vite build passed.
• Live Vite server returned HTTP 200 at 127.0.0.1.
• Targeted repository render test passed.
• Ruff lint and format checks passed.

The full make check reached the existing repository lock-check mismatch: uv.lock needs updating against the reviewed AgentSeek core commit. The remaining lint, format, and pytest run proceeded; 199 tests passed before the long existing runtime smoke suite was interrupted.