refactor: rename review tools for clarity and consistency

- Renamed `review_code` tool to `codereview` for better naming convention
- Renamed `review_changes` tool to `precommit` to better reflect its purpose
- Updated all tool descriptions to remove "Triggers:" sections and improve clarity
- Updated all imports and references throughout the codebase
- Renamed test files to match new tool names
- Updated server.py tool registrations
- All existing functionality preserved with improved naming

This refactoring improves code organization and makes tool purposes clearer.

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

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

tools/__init__.py

@@ -4,16 +4,16 @@ Tool implementations for Gemini MCP Server
 
 from .analyze import AnalyzeTool
 from .chat import ChatTool
+from .codereview import CodeReviewTool
 from .debug import DebugIssueTool
-from .review_changes import ReviewChanges
-from .review_code import ReviewCodeTool
+from .precommit import Precommit
 from .think_deeper import ThinkDeeperTool
 
 __all__ = [
     "ThinkDeeperTool",
-    "ReviewCodeTool",
+    "CodeReviewTool",
     "DebugIssueTool",
     "AnalyzeTool",
     "ChatTool",
-    "ReviewChanges",
+    "Precommit",
 ]