chore: Remove Kong references, make infrastructure examples generic

Replaced Kong-specific examples with generic infrastructure scenarios:
  - Known-answer questions: database timeout, model loading, GPU memory
  - K8s manifest: generic timeout annotations (cloud-provider agnostic)
  - Removed Kong timeouts, routes, plugins
  - Added gateway configuration guidance for various platforms
  - Updated HF token secret management

Benefits:
  - System is now cloud-provider agnostic
  - Works with any gateway (Istio, Nginx, cloud LB, etc.)
  - Examples are more universally applicable
  - Easier to adapt to different infrastructure

Affected files:
  - verify/known-answers.yaml (3 generic scenarios)
  - M3.4-GATE.md (updated expected answers)
  - k8s/apps/llm-serving/memory-isvc.yaml (cloud-agnostic setup)

verify/known-answers.yaml

@@ -5,24 +5,24 @@
 # Used to measure hit rate and provenance precision of the retrieval pipeline.
 
 questions:
-  - id: kong_body_buffer
-    question: "why did requests over 10KB fail?"
-    expected_node_text: "Kong buffer limit 64KB"
-    expected_source_substring: "body size too large"
+  - id: db_query_timeout
+    question: "why are database queries timing out?"
+    expected_node_text: "Missing index on queries table"
+    expected_source_substring: "sequential scan"
     expected_query: "infra-root-causes"
     level: "L1"
 
-  - id: kong_auth_header
-    question: "why did requests with Authorization header fail?"
-    expected_node_text: "Kong key-auth"
-    expected_source_substring: "apikey header"
+  - id: model_load_timeout
+    question: "why does the model fail to load on cold start?"
+    expected_node_text: "Model loading exceeds 60s timeout"
+    expected_source_substring: "torch compile"
     expected_query: "infra-root-causes"
     level: "L1"
 
-  - id: cold_start_timeout
-    question: "what causes the 504 timeout on cold start?"
-    expected_node_text: "Ingress timeout"
-    expected_source_substring: "gateway timeout"
+  - id: memory_pressure
+    question: "what causes out of memory errors?"
+    expected_node_text: "GPU VRAM exhaustion"
+    expected_source_substring: "loaded models eviction"
     expected_query: "infra-root-causes"
     level: "L1"