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>

tests/test_large_prompt_handling.py

@@ -21,7 +21,7 @@ from tools.chat import ChatTool
 from tools.codereview import CodeReviewTool
 from tools.debug import DebugIssueTool
 from tools.precommit import Precommit
-from tools.think_deeper import ThinkDeeperTool
+from tools.thinkdeep import ThinkDeepTool
 
 
 class TestLargePromptHandling:
@@ -131,9 +131,9 @@ class TestLargePromptHandling:
         shutil.rmtree(temp_dir)
 
     @pytest.mark.asyncio
-    async def test_think_deeper_large_analysis(self, large_prompt):
-        """Test that think_deeper tool detects large current_analysis."""
-        tool = ThinkDeeperTool()
+    async def test_thinkdeep_large_analysis(self, large_prompt):
+        """Test that thinkdeep tool detects large current_analysis."""
+        tool = ThinkDeepTool()
         result = await tool.execute({"current_analysis": large_prompt})
 
         assert len(result) == 1