Add comprehensive docstrings, expand API reference, upgrade to Starlette 1.0

- Add docstrings to all undocumented public methods across API, Request,
  Response, Router, Route, BackgroundQueue, and related classes
- Expand api.rst with autodoc sections for RouteGroup, BackgroundQueue,
  QueryDict, and RateLimiter
- Update starlette dependency to >=1.0
- Drop Python 3.9 support (required by Starlette 1.0), minimum is now 3.10
- Bump version to 3.4.0

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/source/api.rst

@@ -43,6 +43,45 @@ status code, headers, and cookies.
     :inherited-members:
 
 
+Route Groups
+------------
+
+Group related routes under a shared URL prefix — useful for API versioning
+and organizing large applications.
+
+.. autoclass:: responder.api.RouteGroup
+    :members:
+
+
+Background Queue
+----------------
+
+Run tasks in background threads without blocking the response. Available
+as ``api.background``.
+
+.. autoclass:: responder.background.BackgroundQueue
+    :members:
+
+
+Query Dict
+----------
+
+A dictionary subclass for query string parameters with multi-value support.
+
+.. autoclass:: responder.models.QueryDict
+    :members:
+
+
+Rate Limiter
+------------
+
+In-memory token bucket rate limiter. Limits requests per client IP address
+and returns ``429 Too Many Requests`` when exceeded.
+
+.. autoclass:: responder.ext.ratelimit.RateLimiter
+    :members:
+
+
 Status Code Helpers
 -------------------
 

docs/source/index.rst

@@ -86,7 +86,7 @@ Installation
 
     $ uv pip install responder
 
-Python 3.9 and above. That's it.
+Python 3.10 and above. That's it.
 
 
 .. toctree::