fix: Import spaces before torch to prevent CUDA initialization error

Problem:
- RuntimeError on ZeroGPU: 'CUDA has been initialized before importing spaces package'
- torch was being imported before spaces could configure ZeroGPU properly

Solution:
- Move spaces import to top of file (before torch, transformers)
- Set ZEROGPU_AVAILABLE at import time instead of after environment detection
- Use already-imported ZEROGPU_AVAILABLE in detect_hardware_environment()
- Remove duplicate ZEROGPU_AVAILABLE assignment

Changes:
- Lines 9-15: Import spaces first with try/except
- Line 84: Use ZEROGPU_AVAILABLE directly instead of re-importing spaces
- Line 138: Remove duplicate assignment, add explanatory comment

This follows ZeroGPU best practice: import spaces before any CUDA package
https://huggingface.co/docs/hub/spaces-zerogpu#basic-usage

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app.py

@@ -5,6 +5,16 @@ Supports: Local (Mac/Linux/Windows), HF Spaces (CPU Basic/Upgrade, ZeroGPU)
 
 import os
 import platform
+
+# IMPORTANT: Import spaces FIRST before any CUDA-related packages (torch, transformers)
+# This prevents "CUDA has been initialized" error on ZeroGPU
+try:
+    import spaces
+    ZEROGPU_AVAILABLE = True
+except ImportError:
+    ZEROGPU_AVAILABLE = False
+
+# Now safe to import CUDA-related packages
 import gradio as gr
 from transformers import AutoModelForCausalLM, AutoTokenizer
 from huggingface_hub import snapshot_download
@@ -70,15 +80,14 @@ def detect_hardware_environment():
         env_info['platform'] = 'hf_spaces'
         space_id = os.environ.get('SPACE_ID', 'unknown')
 
-        # Check for ZeroGPU
-        try:
-            import spaces
+        # Check for ZeroGPU using already-imported status
+        if ZEROGPU_AVAILABLE:
             env_info['hardware'] = 'zerogpu'
             env_info['gpu_available'] = True
             env_info['gpu_name'] = 'NVIDIA H200 (ZeroGPU)'
             env_info['description'] = f"🚀 HF Spaces - ZeroGPU ({space_id})"
             env_info['cuda_compatible'] = True
-        except ImportError:
+        else:
             # Check CPU tier by memory/CPU count
             cpu_count = env_info['cpu_count']
             if cpu_count >= 8:
@@ -126,7 +135,7 @@ def detect_hardware_environment():
 
 # Detect hardware environment
 HW_ENV = detect_hardware_environment()
-ZEROGPU_AVAILABLE = HW_ENV['hardware'] == 'zerogpu'
+# Note: ZEROGPU_AVAILABLE already set at import time to prevent CUDA initialization errors
 
 # Print environment info
 print("=" * 60)