fix: simplify health check to liveness probe

Health check no longer validates Gitea connectivity - this is checked
when tools are actually called. Fixes Docker health check failures when
container networking can't resolve external Gitea URL.

server.py

@@ -338,14 +338,12 @@ async def gitea_api_call(
 
 
 async def health_check(request):
-    """Health check endpoint for Docker/Kubernetes."""
-    is_healthy = await client.health_check()
-    if is_healthy:
+    """Health check endpoint for Docker/Kubernetes.
+    
+    This is a liveness probe - it just confirms the server is running.
+    Gitea connectivity is validated when tools are actually called.
+    """
     return JSONResponse({"status": "ok", "gitea_url": GITEA_URL})
-    return JSONResponse(
-        {"status": "unhealthy", "message": "Cannot connect to Gitea"},
-        status_code=503,
-    )
 
 
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