fix(vllm-phi4): Ollama-matching chat template to recover R15 baseline

vLLM's official Phi-4 tokenizer template emits <|end|> after the system turn;
Ollama's does not. That single boundary token regressed brokkr's R15 P02
admission eval (type macro-F1 -33pp) vs the Ollama-measured canonical, while
valid_format held at 1.0. Operator chose to make vLLM match Ollama's leaner
scaffold globally (baseline == production). Adds conf/phi4-chat-template.jinja
(drops the system <|end|>) + mounts it + --chat-template on vllm-phi4. Applied
prompt verified via tokenize/detokenize; brokkr re-smokes probe_vllm.yaml.

stacks/vllm/compose.yaml

@@ -210,6 +210,7 @@ services:
       - "${PHI4_PORT}:8000"
     volumes:
       - /tank/aimodels/huggingface:/hfcache
+      - /opt/docker/conf/vllm/phi4-chat-template.jinja:/config/phi4-chat-template.jinja:ro
     environment:
       - HF_HOME=/hfcache
       - HF_HUB_CACHE=/hfcache/hub
@@ -237,6 +238,10 @@ services:
       # FP8 KV cache — halves KV memory at 128K ctx on Ada (cc 8.9); near-lossless.
       - --kv-cache-dtype
       - ${PHI4_KV_CACHE_DTYPE}
+      # Ollama-matching scaffold (drops the system-turn <|end|>) so vLLM reproduces
+      # brokkr's R15 canonical baseline. See conf/phi4-chat-template.jinja.
+      - --chat-template
+      - /config/phi4-chat-template.jinja
     deploy:
       resources:
         reservations: