Major updates: LinkedIn auto-posting, timezone fixes, and Docker improvements

Features:
- Add LinkedIn OAuth integration and auto-posting functionality
- Add scheduler service for automated post publishing
- Add metadata field to generated_posts for LinkedIn URLs
- Add privacy policy page for LinkedIn API compliance
- Add company management features and employee accounts
- Add license key system for company registrations

Fixes:
- Fix timezone issues (use UTC consistently across app)
- Fix datetime serialization errors in database operations
- Fix scheduling timezone conversion (local time to UTC)
- Fix import errors (get_database -> db)

Infrastructure:
- Update Docker setup to use port 8001 (avoid conflicts)
- Add SSL support with nginx-proxy and Let's Encrypt
- Add LinkedIn setup documentation
- Add migration scripts for schema updates

Services:
- Add linkedin_service.py for LinkedIn API integration
- Add scheduler_service.py for background job processing
- Add storage_service.py for Supabase Storage
- Add email_service.py improvements
- Add encryption utilities for token storage

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

src/web/app.py

@@ -1,15 +1,47 @@
 """FastAPI web frontend for LinkedIn Post Creation System."""
+from contextlib import asynccontextmanager
 from pathlib import Path
 
 from fastapi import FastAPI
 from fastapi.staticfiles import StaticFiles
 from fastapi.responses import RedirectResponse
+from loguru import logger
 
 from src.config import settings
 from src.web.admin import admin_router
 
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    """Manage application lifecycle - startup and shutdown."""
+    # Startup
+    logger.info("Starting LinkedIn Post Creation System...")
+
+    # Initialize and start scheduler if enabled
+    scheduler = None
+    if settings.user_frontend_enabled:
+        try:
+            from src.database.client import DatabaseClient
+            from src.services.scheduler_service import init_scheduler
+
+            db = DatabaseClient()
+            scheduler = init_scheduler(db, check_interval=60)  # Check every 60 seconds
+            await scheduler.start()
+            logger.info("Scheduler service started")
+        except Exception as e:
+            logger.error(f"Failed to start scheduler: {e}")
+
+    yield  # Application runs here
+
+    # Shutdown
+    logger.info("Shutting down LinkedIn Post Creation System...")
+    if scheduler:
+        await scheduler.stop()
+        logger.info("Scheduler service stopped")
+
+
 # Setup
-app = FastAPI(title="LinkedIn Post Creation System")
+app = FastAPI(title="LinkedIn Post Creation System", lifespan=lifespan)
 
 # Static files
 app.mount("/static", StaticFiles(directory=Path(__file__).parent / "static"), name="static")