Update Python version requirements and fix compatibility issues

- Bump minimum Python version from 3.11 to 3.13 across all apps
- Add Python 3.11-3.13 test matrix to CLI workflow
- Document Python 3.11+ requirement in .env.example
- Fix Starlette Broadcast removal with in-process fallback implementation
- Add _InProcessBroadcast class for tests when Starlette Broadcast is unavailable
- Refactor API key validators to read live settings instead of cached values
- Update database models with explicit

apps/coordinator-api/src/app/schemas.py

@@ -202,6 +202,9 @@ class MinerHeartbeat(BaseModel):
     inflight: int = 0
     status: str = "ONLINE"
     metadata: Dict[str, Any] = Field(default_factory=dict)
+    architecture: Optional[str] = None
+    edge_optimized: Optional[bool] = None
+    network_latency_ms: Optional[float] = None
 
 
 class PollRequest(BaseModel):