fix: Resolve merge conflicts in router quality improvements

Resolved conflicts between router quality improvements and multi-source
synthesis architecture:

1. **unified_skill_builder.py**:
   - Updated _generate_architecture_overview() signature to accept github_data
   - Ensures GitHub metadata is available for enhanced router generation

2. **test_c3_integration.py**:
   - Updated test data structure to multi-source list format
   - Tests now properly mock github data for architecture generation
   - All 8 C3 integration tests passing

**Test Results**:
- ✅ All 8 C3 integration tests pass
- ✅ All 26 unified tests pass
- ✅ All 116 GitHub-related tests pass
- ✅ All 62 multi-source architecture tests pass

The changes maintain backward compatibility while enabling router skills
to leverage GitHub insights (issues, labels, metadata) for better quality.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/skill_seekers/cli/unified_skill_builder.py

@@ -990,7 +990,7 @@ This skill combines knowledge from multiple sources:
         logger.info("Generating C3.x codebase analysis references...")
 
         # Generate ARCHITECTURE.md (main deliverable)
-        self._generate_architecture_overview(c3_dir, c3_data)
+        self._generate_architecture_overview(c3_dir, c3_data, github_data)
 
         # Generate subdirectories for each C3.x component
         self._generate_pattern_references(c3_dir, c3_data.get('patterns'))
@@ -1001,7 +1001,7 @@ This skill combines knowledge from multiple sources:
 
         logger.info("✅ Created codebase analysis references")
 
-    def _generate_architecture_overview(self, c3_dir: str, c3_data: Dict):
+    def _generate_architecture_overview(self, c3_dir: str, c3_data: Dict, github_data: Dict):
         """Generate comprehensive ARCHITECTURE.md (C3.5 main deliverable)."""
         arch_path = os.path.join(c3_dir, 'ARCHITECTURE.md')