feat(podcast): add pre-estimate endpoint, enhance cost estimator with multi-model support, cleanup alpha pricing seeding

- Add POST /podcast/pre-estimate endpoint for cost estimation before analysis
- Enhance cost_estimator.py with multi-model support (gemini, audio, voice clone, image, video)
- Add detailed cost breakdown (llm, audio, media costs + per-phase breakdown)
- Remove redundant pricing seeding from init_alpha_subscription_tiers.py
- Add SSOT pricing via PricingService.initialize_default_pricing()
- Update TopicUrlInput tooltip to show estimate details
- Add debug logging for pricing seeding and pre-estimate
- Clean up verbose podcast mode debug logs in app.py

backend/api/podcast/router.py

@@ -12,7 +12,7 @@ from api.story_writer.utils.auth import require_authenticated_user
 from api.story_writer.task_manager import task_manager
 
 # Import all handler routers
-from .handlers import projects, analysis, research, script, audio, images, video, avatar, dubbing, broll, trends
+from .handlers import projects, analysis, research, script, audio, images, video, avatar, dubbing, broll, trends, tavily_category_research
 
 # Create main router
 router = APIRouter(prefix="/api/podcast", tags=["Podcast Maker"])
@@ -29,6 +29,7 @@ router.include_router(avatar.router)
 router.include_router(dubbing.router)
 router.include_router(broll.router)
 router.include_router(trends.router)
+router.include_router(tavily_category_research.router)
 
 
 @router.get("/task/{task_id}/status")