feat: Zed edit-predictions keyless FIM route (Qwen2.5-Coder-1.5B / coder-fast)

Deep-research-picked Qwen2.5-Coder-1.5B (BASE, Apache-2.0, native FIM) as a
low-latency inline-completion seat:
- stacks/vllm: vllm-coder service (ana-ml2 GPU1 :8020) + granite shrunk
  (util 0.27->0.13, max-len 131072->16384, seqs 1024->256; granite phasing out)
  to free GPU1 room.
- stacks/litellm: coder-fast alias -> :8020 (mode: completion, /v1/completions).
- stacks/zed-fim-proxy (NEW): keyless /v1/completions front door on ana-docker
  :4141 for Zed (which can't send an auth header) — POST + path + model
  allowlist, injects a coder-fast-scoped virtual key -> LiteLLM :4000. Anon
  /ping liveness. Verified keyless FIM end-to-end.

Zed api_url = http://10.250.50.70:4141/v1, model coder-fast, prompt_format qwen.
Source-IP allowlist off pending the Mac's observed source IP.

stacks/vllm/compose.yaml

@@ -278,6 +278,70 @@ services:
       - homepage.description=Granite 4.1 8B FP8 via vLLM (ana-ml2)
       - homepage.href=http://10.250.50.54:${GRANITE_PORT}/docs
 
+  vllm-coder:
+    image: vllm/vllm-openai:${VLLM_VERSION}
+    container_name: vllm-coder
+    restart: unless-stopped
+    ipc: host
+    ports:
+      - "${CODER_PORT}:8000"
+    volumes:
+      - /tank/aimodels/huggingface:/hfcache
+    environment:
+      - HF_HOME=/hfcache
+      - HF_HUB_CACHE=/hfcache/hub
+      - HUGGING_FACE_HUB_TOKEN=${HF_TOKEN:-}
+      - VLLM_API_KEY=${API_KEY:-}
+    command:
+      # Qwen2.5-Coder-1.5B (BASE) — FIM code-completion seat for Zed edit-predictions
+      # (deep-research pick 2026-07-27). Native fill-in-the-middle: <|fim_prefix|> /
+      # <|fim_suffix|> / <|fim_middle|> (IDs 151659/151660/151661); Zed sends the
+      # FIM-formatted prompt to /v1/completions and vLLM passes it through (the FIM
+      # special tokens live in the tokenizer). BASE not -Instruct (FIM is a
+      # pretraining objective; base completions are cleaner). Apache-2.0. Runner-up =
+      # Qwen2.5-Coder-3B (higher HumanEval-FIM but non-commercial Qwen-Research license).
+      - ${CODER_MODEL}
+      - --served-model-name
+      - ${CODER_SERVED_NAME}
+      - --host
+      - 0.0.0.0
+      - --port
+      - "8000"
+      - --gpu-memory-utilization
+      - ${CODER_GPU_MEM_UTIL}
+      - --max-model-len
+      - ${CODER_MAX_MODEL_LEN}
+      - --max-num-seqs
+      - ${CODER_MAX_NUM_SEQS}
+      - --dtype
+      - auto
+      - --kv-cache-dtype
+      - ${CODER_KV_CACHE_DTYPE}
+      - --enable-prefix-caching
+    deploy:
+      resources:
+        reservations:
+          devices:
+            - driver: nvidia
+              device_ids:
+                - "${CODER_GPU_ID}"
+              capabilities:
+                - gpu
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://localhost:8000/health"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 300s
+    networks:
+      - tnet
+    labels:
+      - homepage.group=AI - Inference
+      - homepage.name=vLLM Qwen2.5-Coder 1.5B (FIM)
+      - homepage.icon=mdi-code-braces
+      - homepage.description=Qwen2.5-Coder-1.5B FIM code-completion (ana-ml2, Zed edit-predictions)
+      - homepage.href=http://10.250.50.54:${CODER_PORT}/docs
+
 networks:
   tnet:
     name: traefik-net