fix(executor): improve antigravity reverse proxy emulation

- force http/1.1 instead of http/2

- explicit connection close

- strip proxy headers X-Forwarded-For and X-Real-IP

- add project id to fetch models payload

internal/api/modules/amp/proxy.go

@@ -73,6 +73,10 @@ func createReverseProxy(upstreamURL string, secretSource SecretSource) (*httputi
 		req.Header.Del("Authorization")
 		req.Header.Del("X-Api-Key")
 		req.Header.Del("X-Goog-Api-Key")
+		
+		// Remove proxy tracing headers to avoid upstream detection
+		req.Header.Del("X-Forwarded-For")
+		req.Header.Del("X-Real-IP")
 
 		// Remove query-based credentials if they match the authenticated client API key.
 		// This prevents leaking client auth material to the Amp upstream while avoiding