Extract commentary system to routes/commentary.py

- Create new commentary module (4,130 lines) containing:
  - Commentary route handler
  - All commentary generation functions
  - Book introduction and historical context generators
  - Literary features, themes, and theological significance
  - Word study sidenotes and verse analysis

- Update routes/__init__.py with new exports

- Reduce server.py from 7,100+ to 2,394 lines (-66% reduction)

All 100 tests passing.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

kjvstudy_org/routes/__init__.py

@@ -5,10 +5,12 @@ from .api import router as api_router
 from .resources import router as resources_router, init_templates as init_resources_templates
 from .family_tree import router as family_tree_router, init_templates as init_family_tree_templates
 from .study_guides import router as study_guides_router, init_templates as init_study_guides_templates
+from .commentary import router as commentary_router, init_templates as init_commentary_templates
 
 __all__ = [
     'api_router',
     'resources_router', 'init_resources_templates',
     'family_tree_router', 'init_family_tree_templates',
     'study_guides_router', 'init_study_guides_templates',
+    'commentary_router', 'init_commentary_templates',
 ]