refactor: Convert to UV Python project with proper package structure

- Restructured project to use src/stocktool package layout
- Migrated to UV for dependency management
- Added pyproject.toml with all dependencies (sv-ttk, pillow, requests, pyyaml)
- Organized test files into tests/ directory
- Updated .gitignore for UV projects
- Comprehensive README with installation and usage instructions
- Removed old unused files (main.py, stock_tool_gui.py, duplicate copy)
- Added CLI entry point: stock-tool command

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

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

tests/test_add_stock.py

@@ -0,0 +1,67 @@
+#!/usr/bin/env python3
+"""Test script to verify the add stock response handling."""
+
+def handle_add_stock_response(response_data):
+    """
+    Simulate the add stock response handling logic.
+
+    Args:
+        response_data: The response from POST /api/stock/
+
+    Returns:
+        Stock item ID
+    """
+    if isinstance(response_data, list):
+        # If it's a list, get the first item
+        stock_item = response_data[0] if response_data else {}
+    else:
+        # If it's a dict, use it directly
+        stock_item = response_data
+
+    sid = stock_item.get('pk', stock_item.get('id'))
+    return sid
+
+
+print("Testing add stock response handling:\n")
+
+# Test 1: Response is a dict with 'pk' key
+print("Test 1: API returns dict with 'pk'")
+response = {'pk': 123, 'quantity': 150, 'part': 456, 'location': 476}
+sid = handle_add_stock_response(response)
+print(f"  Response: {response}")
+print(f"  Stock ID: {sid}")
+print(f"  Expected: 123, Got: {sid} - {'PASS' if sid == 123 else 'FAIL'}\n")
+
+# Test 2: Response is a dict with 'id' key
+print("Test 2: API returns dict with 'id'")
+response = {'id': 456, 'quantity': 150, 'part': 789, 'location': 476}
+sid = handle_add_stock_response(response)
+print(f"  Response: {response}")
+print(f"  Stock ID: {sid}")
+print(f"  Expected: 456, Got: {sid} - {'PASS' if sid == 456 else 'FAIL'}\n")
+
+# Test 3: Response is a list with dict containing 'pk'
+print("Test 3: API returns list with dict containing 'pk'")
+response = [{'pk': 789, 'quantity': 150, 'part': 123, 'location': 476}]
+sid = handle_add_stock_response(response)
+print(f"  Response: {response}")
+print(f"  Stock ID: {sid}")
+print(f"  Expected: 789, Got: {sid} - {'PASS' if sid == 789 else 'FAIL'}\n")
+
+# Test 4: Response is a list with dict containing 'id'
+print("Test 4: API returns list with dict containing 'id'")
+response = [{'id': 999, 'quantity': 150, 'part': 123, 'location': 476}]
+sid = handle_add_stock_response(response)
+print(f"  Response: {response}")
+print(f"  Stock ID: {sid}")
+print(f"  Expected: 999, Got: {sid} - {'PASS' if sid == 999 else 'FAIL'}\n")
+
+# Test 5: Empty response
+print("Test 5: API returns empty dict")
+response = {}
+sid = handle_add_stock_response(response)
+print(f"  Response: {response}")
+print(f"  Stock ID: {sid}")
+print(f"  Expected: None, Got: {sid} - {'PASS' if sid is None else 'FAIL'}\n")
+
+print("All tests completed!")