Update confidence enum values across workflow tools

Added new confidence values (very_high, almost_certain) to all workflow tools
to provide more granular confidence tracking. Updated enum declarations in:
- analyze.py, codereview.py, debug.py, precommit.py, secaudit.py, testgen.py
- Updated debug.py's get_required_actions to handle new confidence values
- All tools now use consistent 7-value confidence scale
- refactor.py kept its unique scale (exploring/incomplete/partial/complete)

Also fixed model thinking configuration:
- Added very_high and almost_certain to MODEL_THINKING_PREFERENCES
- Set medium thinking for very_high, high thinking for almost_certain
- Updated prompts to clarify certain means 100% local confidence

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

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

tests/test_chat_simple.py

@@ -119,7 +119,7 @@ class TestChatTool:
         formatted = self.tool.format_response(response, request)
 
         assert "Test response content" in formatted
-        assert "Claude's Turn:" in formatted
+        assert "AGENT'S TURN:" in formatted
         assert "Evaluate this perspective" in formatted
 
     def test_tool_name(self):