feat: add capacity planning docs, image upload system, and platform health monitoring

Documentation:
- Add comprehensive capacity planning guide (docs/architecture/capacity-planning.md)
- Add operations docs: platform-health, capacity-monitoring, image-storage
- Link pricing strategy to capacity planning documentation
- Update mkdocs.yml with new Operations section

Image Upload System:
- Add ImageService with WebP conversion and sharded directory structure
- Generate multiple size variants (original, 800px, 200px)
- Add storage stats endpoint for monitoring
- Add Pillow dependency for image processing

Platform Health Monitoring:
- Add /admin/platform-health page with real-time metrics
- Show CPU, memory, disk usage with progress bars
- Display capacity thresholds with status indicators
- Generate scaling recommendations automatically
- Determine infrastructure tier based on usage
- Add psutil dependency for system metrics

Admin UI:
- Add Capacity Monitor to Platform Health section in sidebar
- Create platform-health.html template with stats cards
- Create platform-health.js for Alpine.js state management

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

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

app/api/v1/admin/__init__.py

@@ -33,6 +33,7 @@ from . import (
     content_pages,
     customers,
     dashboard,
+    images,
     inventory,
     letzshop,
     logs,
@@ -42,6 +43,7 @@ from . import (
     notifications,
     order_item_exceptions,
     orders,
+    platform_health,
     products,
     settings,
     tests,
@@ -162,6 +164,14 @@ router.include_router(messages.router, tags=["admin-messages"])
 # Include log management endpoints
 router.include_router(logs.router, tags=["admin-logs"])
 
+# Include image management endpoints
+router.include_router(images.router, tags=["admin-images"])
+
+# Include platform health endpoints
+router.include_router(
+    platform_health.router, prefix="/platform", tags=["admin-platform-health"]
+)
+
 
 # ============================================================================
 # Code Quality & Architecture