feat: Add Signal-Based How-To Guides (C3.10.1) - Complete C3.10

Final piece of Signal Flow Analysis - AI-generated tutorial guides:

## Signal-Based How-To Guides (C3.10.1)
Completes the 5th and final proposed feature for C3.10.

### Implementation
Added to SignalFlowAnalyzer class:
- extract_signal_usage_patterns(): Identifies top 10 most-used signals
- generate_how_to_guides(): Creates tutorial-style guides
- _generate_signal_guide(): Builds structured guide for each signal

### Guide Structure (3-Step Pattern)
Each guide includes:
1. **Step 1: Connect to the signal**
   - Code example with actual handler names from codebase
   - File context (which file to add connection in)

2. **Step 2: Emit the signal**
   - Code example with actual parameters from codebase
   - File context (where emission happens)

3. **Step 3: Handle the signal**
   - Function implementation template
   - Proper parameter handling

4. **Common Usage Locations**
   - Connected in: file.gd → handler()
   - Emitted from: file.gd

### Output
Generates signal_how_to_guides.md with:
- Table of Contents (10 signals)
- Tutorial guide for each signal
- Real code examples extracted from codebase
- Actual file locations and handler names

### Test Results (Cosmic Ideler)
Generated guides for 10 most-used signals:
- camera_3d_resource_property_changed (most used)
- changed
- wait_started
- dead_zone_changed
- display_refresh_needed
- pressed
- pcam_priority_override
- dead_zone_reached
- noise_emitted
- viewfinder_update

File: signal_how_to_guides.md (6.1KB)

## C3.10 Status: 5/5 Features Complete ✅

1. ✅ Signal Connection Mapping (634 connections tracked)
2. ✅ Event-Driven Architecture Detection (3 patterns)
3. ✅ Signal Flow Visualization (Mermaid diagrams)
4. ✅ Signal Documentation Extraction (docs in reference)
5. ✅ Signal-Based How-To Guides (10 tutorials) - NEW

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

src/skill_seekers/cli/codebase_scraper.py

@@ -1180,7 +1180,7 @@ def analyze_codebase(
         logger.info("Analyzing signal flow patterns (Godot)...")
         try:
             signal_analyzer = SignalFlowAnalyzer(results)
-            signal_output = signal_analyzer.save_analysis(output_dir)
+            signal_output = signal_analyzer.save_analysis(output_dir, ai_mode)
             signal_analysis = signal_analyzer.analyze()
 
             stats = signal_analysis["statistics"]