chore: replace hypercorn with granian (Rust ASGI server)

Granian is ~3-5x faster than Hypercorn in benchmarks. No code changes
needed — Quart is standard ASGI so any ASGI server works.

- web/pyproject.toml: hypercorn → granian>=1.6.0 (installed: 2.7.1)
- Dockerfile CMD: hypercorn → granian --interface asgi
- core.py setup_logging(): silence granian loggers instead of hypercorn's

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

web/pyproject.toml

@@ -10,7 +10,7 @@ dependencies = [
     "python-dotenv>=1.0.0",
     "itsdangerous>=2.1.0",
     "jinja2>=3.1.0",
-    "hypercorn>=0.17.0",
+    "granian>=1.6.0",
     "paddle-python-sdk>=1.13.0",
     "mistune>=3.0.0",
     "resend>=2.22.0",