Add LLM endpoints, web frontend, and rate limiting config

- Added OpenAI-compatible LLM endpoints to API backend - Introduced web
frontend with Jinja2 templates and static assets - Implemented API proxy
routes in web service - Added sample db.json data for items, users,
orders, reviews, categories, llm_requests - Updated ADC and Helm configs
for separate AI and standard rate limiting - Upgraded FastAPI, Uvicorn,
and added httpx, Jinja2, python-multipart dependencies - Added API
configuration modal and client-side JS for web app

helm/api7ee-demo-k8s/values.yaml

@@ -247,7 +247,16 @@ api7:
 
   # API7 Plugins Configuration
   plugins:
-    # AI Rate limiting (for /api route)
+    # Standard Rate limiting (for /api route - per IP)
+    rateLimit:
+      enabled: true
+      count: 100
+      timeWindow: 60
+      rejectedCode: 429
+      keyType: "var"
+      key: "remote_addr"
+
+    # AI Rate limiting (for /api/llm route)
     aiRateLimit:
       enabled: true
       limit: 100