Upgrade to kaya 0.0.2 and run on the rloop event loop

- pin kaya-core/kaya-rsgi >= 0.0.2 (ctx.client now honors Forwarded and
  X-Forwarded-* headers); adapt route tests and add explicit coverage
- add rloop dependency and set GRANIAN_LOOP=rloop in the Docker image so
  granian serves the app on the Rust event loop instead of asyncio
- regenerate requirements.txt (kaya 0.0.2, rloop 0.5.0)
- document the new loop and forwarded-header behavior in the README

requirements.txt

@@ -29,17 +29,19 @@ idna==3.19
     # via
     #   anyio
     #   httpx
-kaya-core==0.0.1
+kaya-core==0.0.2
     # via
     #   kaya-rsgi
     #   pyfconfig (pyproject.toml)
-kaya-rsgi==0.0.1
+kaya-rsgi==0.0.2
     # via pyfconfig (pyproject.toml)
 pwo==0.1.2
     # via
     #   kaya-core
     #   kaya-rsgi
     #   pyfconfig (pyproject.toml)
+rloop==0.5.0
+    # via pyfconfig (pyproject.toml)
 typing-extensions==4.16.0
     # via
     #   anyio