feat: C3.9 documentation extraction, AI enhancement optimization, and C# support

Complete implementation of C3.9, granular AI enhancement control, performance optimizations, and bug fixes.

Features:
- C3.9 Project Documentation Extraction (markdown files)
- Granular AI enhancement control (--enhance-level 0-3)
- C# test extraction support
- 6-12x faster LOCAL mode with parallel execution
- Auto-enhancement UX improvements
- LOCAL mode fallback for all AI enhancements

Bug Fixes:
- C# language support
- Config type field compatibility
- LocalSkillEnhancer import

Documentation:
- Updated CHANGELOG.md
- Updated CLAUDE.md
- Removed client-specific files

Tests: All 1,257 tests passing
Critical linter errors: Fixed

CLAUDE.md

@@ -297,9 +297,17 @@ skill-seekers analyze --directory . --skip-patterns --skip-how-to-guides
 ```
 
 - Generates 300+ line standalone SKILL.md files from codebases
-- All C3.x features integrated (patterns, tests, guides, config, architecture)
+- All C3.x features integrated (patterns, tests, guides, config, architecture, docs)
 - Complete codebase analysis without documentation scraping
 
+**C3.9 Project Documentation Extraction** (`codebase_scraper.py`):
+- Extracts and categorizes all markdown files from the project
+- Auto-detects categories: overview, architecture, guides, workflows, features, etc.
+- Integrates documentation into SKILL.md with summaries
+- AI enhancement (level 2+) adds topic extraction and cross-references
+- Controlled by depth: surface=raw copy, deep=parse+summarize, full=AI-enhanced
+- Default ON, use `--skip-docs` to disable
+
 **Key Architecture Decision (BREAKING in v2.5.2):**
 - Changed from opt-in (`--build-*`) to opt-out (`--skip-*`) flags
 - All analysis features now ON by default for maximum value