docs: add redirects for 13 pages moved from /nvcf/dev/ to /nvcf/

[pdmack]

Description

13 docs pages moved from /nvcf/dev/ to /nvcf/ without redirects in docs.yml. Anyone with a bookmarked or linked /nvcf/dev/ URL gets a 404. Fern surfaces these as warnings on every fern check run.

Pages affected:

Old URL	New URL
/nvcf/dev/function-autoscaling-overview	/nvcf/function-autoscaling-overview
/nvcf/dev/function-lifecycle	/nvcf/function-lifecycle
/nvcf/dev/generic-http-function-invocation	/nvcf/generic-http-function-invocation
/nvcf/dev/g-rpc-load-test-sli-guide	/nvcf/g-rpc-load-test-sli-guide
/nvcf/dev/http-load-testing	/nvcf/http-load-testing
/nvcf/dev/http-load-test-sli-guide	/nvcf/http-load-test-sli-guide
/nvcf/dev/llm-api-gateway	/nvcf/llm-api-gateway
/nvcf/dev/llm-function-invocation-metrics-report	/nvcf/llm-function-invocation-metrics-report
/nvcf/dev/llm-request-router	/nvcf/llm-request-router
/nvcf/dev/managed-observability	/nvcf/managed-observability
/nvcf/dev/monitoring	/nvcf/monitoring
/nvcf/dev/operations	/nvcf/operations
/nvcf/dev/registry-allowlist	/nvcf/registry-allowlist

Definition of Done

• All 13 source/destination pairs added to the redirects block in fern/docs.yml
• fern check runs with 0 warnings for moved-page redirects