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>

tools/workflow/schema_builders.py

@@ -65,7 +65,7 @@ class WorkflowSchemaBuilder:
         },
         "confidence": {
             "type": "string",
-            "enum": ["exploring", "low", "medium", "high", "certain"],
+            "enum": ["exploring", "low", "medium", "high", "very_high", "almost_certain", "certain"],
             "description": WORKFLOW_FIELD_DESCRIPTIONS["confidence"],
         },
         "hypothesis": {