fix(infra): escape \$\$SERVE_PID in compose command to prevent interpolation (#737)

Docker Compose interpolates $VAR in command strings — use $$ to pass a
literal $ to the shell so SERVE_PID=$! and kill $SERVE_PID work correctly.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -162,7 +162,7 @@ services:
     security_opt:
       - no-new-privileges:true
     command: >
-      sh -c "ollama serve & SERVE_PID=$! && until curl -sf http://localhost:11434/api/tags; do sleep 1; done && ollama pull qwen2.5:7b-instruct-q4_K_M && kill $SERVE_PID"
+      sh -c "ollama serve & SERVE_PID=$$! && until curl -sf http://localhost:11434/api/tags; do sleep 1; done && ollama pull qwen2.5:7b-instruct-q4_K_M && kill $$SERVE_PID"
 
   # --- Ollama: LLM inference server ---
   # Serves the pre-pulled model for NL search inference.