Add unified multi-source scraping feature (Phases 7-11)

Completes the unified scraping system implementation:

**Phase 7: Unified Skill Builder**
- cli/unified_skill_builder.py: Generates final skill structure
- Inline conflict warnings (⚠️) in API reference
- Side-by-side docs vs code comparison
- Severity-based conflict grouping
- Separate conflicts.md report

**Phase 8: MCP Integration**
- skill_seeker_mcp/server.py: Auto-detects unified vs legacy configs
- Routes to unified_scraper.py or doc_scraper.py automatically
- Supports merge_mode parameter override
- Maintains full backward compatibility

**Phase 9: Example Unified Configs**
- configs/react_unified.json: React docs + GitHub
- configs/django_unified.json: Django docs + GitHub
- configs/fastapi_unified.json: FastAPI docs + GitHub
- configs/fastapi_unified_test.json: Test config with limited pages

**Phase 10: Comprehensive Tests**
- cli/test_unified_simple.py: Integration tests (all passing)
- Tests unified config validation
- Tests backward compatibility
- Tests mixed source types
- Tests error handling

**Phase 11: Documentation**
- docs/UNIFIED_SCRAPING.md: Complete guide (1000+ lines)
- Examples, best practices, troubleshooting
- Architecture diagrams and data flow
- Command reference

**Additional:**
- demo_conflicts.py: Interactive conflict detection demo
- TEST_RESULTS.md: Complete test results and findings
- cli/unified_scraper.py: Fixed doc_scraper integration (subprocess)

**Features:**
✅ Multi-source scraping (docs + GitHub + PDF)
✅ Conflict detection (4 types, 3 severity levels)
✅ Rule-based merging (fast, deterministic)
✅ Claude-enhanced merging (AI-powered)
✅ Transparent conflict reporting
✅ MCP auto-detection
✅ Backward compatibility

**Test Results:**
- 6/6 integration tests passed
- 4 unified configs validated
- 3 legacy configs backward compatible
- 5 conflicts detected in test data
- All documentation complete

🤖 Generated with Claude Code

configs/fastapi_unified.json

@@ -0,0 +1,45 @@
+{
+  "name": "fastapi",
+  "description": "Complete FastAPI knowledge combining official documentation and FastAPI codebase. Use when building FastAPI applications, understanding async patterns, or working with Pydantic models.",
+  "merge_mode": "rule-based",
+  "sources": [
+    {
+      "type": "documentation",
+      "base_url": "https://fastapi.tiangolo.com/",
+      "extract_api": true,
+      "selectors": {
+        "main_content": "article",
+        "title": "h1",
+        "code_blocks": "pre code"
+      },
+      "url_patterns": {
+        "include": [],
+        "exclude": ["/img/", "/js/"]
+      },
+      "categories": {
+        "getting_started": ["tutorial", "first-steps"],
+        "path_operations": ["path-params", "query-params", "body"],
+        "dependencies": ["dependencies"],
+        "security": ["security", "oauth2"],
+        "database": ["sql-databases"],
+        "advanced": ["advanced", "async", "middleware"],
+        "deployment": ["deployment"]
+      },
+      "rate_limit": 0.5,
+      "max_pages": 150
+    },
+    {
+      "type": "github",
+      "repo": "tiangolo/fastapi",
+      "include_issues": true,
+      "max_issues": 100,
+      "include_changelog": true,
+      "include_releases": true,
+      "include_code": true,
+      "code_analysis_depth": "surface",
+      "file_patterns": [
+        "fastapi/**/*.py"
+      ]
+    }
+  ]
+}