fix: log sidecar switch failures + fix scoping bug in proxy handler

Two changes to debug the fallback-to-LXC issue:

1. Added debug logging on switch failure: prints the profile name,
   sidecar response status, and error message. Also calls
   circuit_record_failure() so subsequent requests don't wait the
   full 120-second timeout before falling back.

2. Fixed scoping bug: sidecar_status was only defined inside the
   else branch of the circuit breaker check. Initialized to None
   at function scope alongside target_url and error to prevent
   NameError when circuit is open.

main.py

@@ -401,6 +401,7 @@ async def proxy(
     # ── Determine target URL ──────────────────────────────────────────────
     target_url: Optional[str] = None
     error: Optional[str] = None
+    sidecar_status = None
 
     # Circuit breaker check
     if not await circuit_breaker_check():
@@ -487,6 +488,13 @@ async def proxy(
                         target_url = f"{MAIN_PC_BASE}/{path}"
                     else:
                         error = "switch_failed"
+                        circuit_record_failure()
+                        print(
+                            f"SWITCH FAILED: profile={requested_model}, "
+                            f"sidecar_status={switch_result.get('status')}, "
+                            f"message={switch_result.get('message', '(no message)')}",
+                            flush=True,
+                        )
                 except Exception as e:
                     circuit_record_failure()
                     error = f"switch_error: {str(e)}"