refactor: rename think_deeper to thinkdeep for brevity

- Renamed `think_deeper` tool to `thinkdeep` for shorter, cleaner naming
- Updated all imports from ThinkDeeperTool to ThinkDeepTool
- Updated all references from THINK_DEEPER_PROMPT to THINKDEEP_PROMPT
- Updated tool registration in server.py
- Updated all test files to use new naming convention
- Updated README documentation to reflect new tool names
- All functionality remains the same, only naming has changed

This completes the tool renaming refactor for improved clarity and consistency.

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

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

tools/__init__.py

@@ -7,10 +7,10 @@ from .chat import ChatTool
 from .codereview import CodeReviewTool
 from .debug import DebugIssueTool
 from .precommit import Precommit
-from .think_deeper import ThinkDeeperTool
+from .thinkdeep import ThinkDeepTool
 
 __all__ = [
-    "ThinkDeeperTool",
+    "ThinkDeepTool",
     "CodeReviewTool",
     "DebugIssueTool",
     "AnalyzeTool",