refactor: rename debug_issue tool to debug for brevity

- Rename debug_issue.py to debug.py
- Update tool name from 'debug_issue' to 'debug' throughout codebase
- Update all references in server.py, tests, and README
- Keep DebugIssueTool class name for backward compatibility
- All tests pass with the renamed tool

This makes the tool name shorter and more consistent with other
tool names like 'chat' and 'analyze'. The functionality remains
exactly the same.

🤖 Generated with Claude Code

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

tests/test_collaboration.py

@@ -8,7 +8,7 @@ from unittest.mock import Mock, patch
 import pytest
 
 from tools.analyze import AnalyzeTool
-from tools.debug_issue import DebugIssueTool
+from tools.debug import DebugIssueTool
 from tools.models import ClarificationRequest, ToolOutput
 
 
@@ -122,7 +122,7 @@ class TestDynamicContextRequests:
                 "question": "I need to see the database configuration to diagnose the connection error",
                 "files_needed": ["config/database.yml", "src/db.py"],
                 "suggested_next_action": {
-                    "tool": "debug_issue",
+                    "tool": "debug",
                     "args": {
                         "error_description": "Connection timeout to database",
                         "files": [
@@ -155,7 +155,7 @@ class TestDynamicContextRequests:
 
         clarification = json.loads(response_data["content"])
         assert "suggested_next_action" in clarification
-        assert clarification["suggested_next_action"]["tool"] == "debug_issue"
+        assert clarification["suggested_next_action"]["tool"] == "debug"
 
     def test_tool_output_model_serialization(self):
         """Test ToolOutput model serialization"""