feat(phase-3): Complete AI content generation system

- Add /api/generate endpoints for AI content generation
- Integrate DeepSeek AI into dashboard compose page
- Add content templates for tips, products, services, engagement
- Implement batch generation for weekly/monthly calendars
- Add cost estimation endpoint

New endpoints:
- POST /api/generate/tip - Generate tech tips
- POST /api/generate/product - Generate product posts
- POST /api/generate/service - Generate service posts
- POST /api/generate/thread - Generate educational threads
- POST /api/generate/response - Generate response suggestions
- POST /api/generate/adapt - Adapt content to platform
- POST /api/generate/improve - Improve existing content
- POST /api/generate/batch - Batch generate for calendar
- GET /api/generate/batch/estimate - Estimate batch costs
- GET /api/generate/status - Check AI connection

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

app/data/__init__.py

@@ -0,0 +1,31 @@
+"""
+Data module - templates and static data for content generation.
+"""
+
+from app.data.content_templates import (
+    TIP_TEMPLATES,
+    PRODUCT_TEMPLATES,
+    SERVICE_TEMPLATES,
+    ENGAGEMENT_TEMPLATES,
+    THREAD_TEMPLATES,
+    OPTIMAL_POSTING_TIMES,
+    get_tip_template,
+    get_product_template,
+    get_service_template,
+    get_engagement_template,
+    get_optimal_times,
+)
+
+__all__ = [
+    "TIP_TEMPLATES",
+    "PRODUCT_TEMPLATES",
+    "SERVICE_TEMPLATES",
+    "ENGAGEMENT_TEMPLATES",
+    "THREAD_TEMPLATES",
+    "OPTIMAL_POSTING_TIMES",
+    "get_tip_template",
+    "get_product_template",
+    "get_service_template",
+    "get_engagement_template",
+    "get_optimal_times",
+]