merge main: resolve conflicts and apply standardized container names

Merge origin/main into feat/standardize-container-names to resolve
merge conflicts.

Resolve modify/delete conflicts:
- DeepSeek-V3.1.yaml, GLM-5.yaml, gpt-oss-single.yaml: deleted on
  main (consolidated into other files); keep deletion.

Resolve content conflicts by starting from main's version and
re-applying the PR's naming conventions:

- nginx → proxy-nginx
- vllm-proxy-* → proxy-*
- glm51 → model-sg-glm51
- qwen35-1/2 → model-sg-qwen35-122b-1/2 (now SGLang on main)
- vllm-qwen3-30b → model-vllm-qwen3-30b
- vllm-gpt-oss-* → model-vllm-gpt-oss-*
- vllm-qwen3-6-35b-* → model-sg-qwen3-6-35b-*
- vllm-gemma-4-31b → model-sg-gemma-4-31b (now SGLang on main)
- vllm-flux-2-klein-4b-1 → model-sg-flux-2-klein-4b-1
- vllm-qwen3-vl → model-vllm-qwen3-vl
- vllm-qwen3-embeddings → model-vllm-qwen3-embeddings
- vllm-qwen3-reranker → model-vllm-qwen3-reranker
- vllm-whisper3-large → model-vllm-whisper3-large
- privacy-filter → model-privacy-filter

All internal references updated: VLLM_BASE_URL, VLLM_BACKEND_URLS,
openmetrics endpoints, registrar health checks, nginx proxy_pass
directives, and Datadog service labels.

Also: add sglang:* metric filter to FLUX Datadog openmetrics config
(matching what Qwen3.6 and Gemma-4 already use).

Author: Lloyd