Finish external HTTP client resilience: add shared aiohttp config, retry support, and update task status

backend/app/config.py

@@ -60,6 +60,26 @@ class Settings(BaseSettings):
             "Ignored when session_cache_enabled is false."
         ),
     )
+    http_request_timeout_seconds: float = Field(
+        default=20.0,
+        ge=0.0,
+        description="Maximum total time in seconds for outbound external HTTP requests.",
+    )
+    http_connect_timeout_seconds: float = Field(
+        default=5.0,
+        ge=0.0,
+        description="Maximum time in seconds to establish outbound external HTTP connections.",
+    )
+    http_max_connections: int = Field(
+        default=10,
+        ge=1,
+        description="Maximum number of concurrent outbound HTTP connections.",
+    )
+    http_keepalive_timeout_seconds: float = Field(
+        default=15.0,
+        ge=0.0,
+        description="How long idle keepalive connections are retained by the HTTP connector.",
+    )
     timezone: str = Field(
         default="UTC",
         description="IANA timezone name used when displaying timestamps in the UI.",