Catch SDK-wrapped GPU errors that bypass CUDA error detection

The ZeroGPU SDK catches CUDA errors internally and re-raises its own
exception type (e.g. "GPU task aborted") which didn't match our error
patterns, causing the bare `raise` to propagate to the UI. Now:
- Add "gpu task aborted" to CUDA error patterns
- Log exception type/message for all GPU errors (aids debugging)
- Replace bare `raise` with catch-all CPU fallback for unrecognized errors
- Only timeouts still re-raise; everything else falls back to CPU

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -50,5 +50,6 @@ models/
 captures/
 
 docs/api.md
+docs/usage-logging.md
 scripts/
 tests/

src/core/zero_gpu.py

@@ -55,6 +55,7 @@ _CUDA_ERROR_PATTERNS = (
     "cuda error", "cuda out of memory",
     "cuda driver", "cuda runtime",
     "device-side assert", "cublas", "cudnn error", "nccl",
+    "gpu task aborted",  # ZeroGPU SDK wraps CUDA errors with this message
 )
 
 try:
@@ -310,6 +311,7 @@ def gpu_with_fallback(duration=60):
             try:
                 return gpu_func(*args, **kwargs)
             except Exception as e:
+                print(f"[GPU] gpu_func error: {type(e).__name__}: {e}")
                 # ZeroGPU raises gradio.Error with title="ZeroGPU quota exceeded"
                 is_quota_error = getattr(e, 'title', '') == "ZeroGPU quota exceeded"
                 if not is_quota_error:
@@ -359,7 +361,18 @@ def gpu_with_fallback(duration=60):
                 )
                 if is_timeout:
                     print(f"[GPU] Timeout error in {func.__name__}: {e}")
-                raise
+                    raise
+
+                # Unrecognized GPU/SDK error — fall back to CPU rather than crash.
+                # Don't mark CUDA unhealthy (might be transient SDK issue).
+                print(f"[GPU] Unrecognized GPU error, falling back to CPU: {type(e).__name__}: {e}")
+                _request_state.gpu_quota_exhausted = True
+                try:
+                    import gradio as gr
+                    gr.Warning("GPU error — using CPU (slower).")
+                except Exception:
+                    pass
+                return func(*args, **kwargs)
 
         return wrapper
     return decorator