feat: add llama-server-fast, a small non-thinking classifier model

Second, always-resident llama.cpp instance (Qwen3-4B-Instruct-2507,
Q8_0 GGUF, ~5GB VRAM) alongside the existing Qwen3.8-27B instance, for
use as qwen-code CLI's Auto Mode classifier fastModel. Model choice
researched in docs/research/fast-model-choice.md: architecturally
non-thinking (unlike Qwen3-1.7B/0.6B), --reasoning off added
defensively per a known (closed) llama.cpp misdetection bug.

- docker-compose.yml: llama-server-fast + downloader-fast services,
  omniroute depends_on updated
- .env.example: LLAMA_FAST_* vars
- scripts/update.sh: runs the new downloader profile

Refs #44

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MrnMEdzeQzqZE5soVEXPCx

docker-compose.yml

@@ -39,6 +39,46 @@ services:
       - "lazytainer.group.llamaserver.inactiveTimeout=${LAZYTAINER_INACTIVE_TIMEOUT:-900}"
       - "lazytainer.group.llamaserver.minPacketThreshold=2"
 
+  llama-server-fast:
+    image: ghcr.io/ggml-org/llama.cpp:server-rocm
+    container_name: llama-server-fast
+    devices:
+      - /dev/kfd
+      - /dev/dri
+    group_add:
+      - video
+      - render
+    security_opt:
+      - seccomp=unconfined
+    ipc: host
+    volumes:
+      - models:/models
+    command: >
+      -m /models/${LLAMA_FAST_MODEL_FILE:-Qwen3-4B-Instruct-2507-UD-Q8_K_XL.gguf}
+      --host 0.0.0.0
+      --port 8080
+      --n-gpu-layers ${LLAMA_FAST_GPU_LAYERS:-999}
+      --ctx-size ${LLAMA_FAST_CTX_SIZE:-8192}
+      --parallel ${LLAMA_FAST_PARALLEL:-2}
+      --flash-attn on
+      --cache-type-k q8_0
+      --cache-type-v q8_0
+      --reasoning off
+      --jinja
+    # Second, always-resident llama.cpp instance — small non-thinking model
+    # used as qwen-code's Auto Mode classifier fastModel, alongside the main
+    # 27B instance above. See docs/research/fast-model-choice.md and #44.
+    # Same ai-stack-only pattern as llama-server: no published host port.
+    expose:
+      - "8080"
+    restart: unless-stopped
+    networks: [ai-stack]
+    labels:
+      - "lazytainer.group.llamaserverfast.sleepMethod=stop"
+      - "lazytainer.group.llamaserverfast.ports=8080"
+      - "lazytainer.group.llamaserverfast.inactiveTimeout=${LAZYTAINER_INACTIVE_TIMEOUT:-900}"
+      - "lazytainer.group.llamaserverfast.minPacketThreshold=2"
+
   # ponytail: one-off downloader, not a standing service — run via
   # `docker compose --profile tools run --rm downloader`. Folded into
   # scripts/update.sh, which runs this every time; the `test -f` guard is
@@ -60,6 +100,22 @@ services:
         curl -L --fail --create-dirs -o /models/${LLAMA_MODEL_FILE:-Qwen3.8-27B-UD-Q4_K_XL.gguf}
         https://huggingface.co/unsloth/Qwen3.8-27B-GGUF/resolve/main/${LLAMA_MODEL_FILE:-Qwen3.8-27B-UD-Q4_K_XL.gguf}
 
+  # Same test -f guard pattern as downloader above — fetches the second,
+  # smaller model for llama-server-fast. See issue #44.
+  downloader-fast:
+    image: curlimages/curl:latest
+    profiles: ["tools"]
+    user: root
+    volumes:
+      - models:/models
+    entrypoint: ["sh", "-c"]
+    command:
+      - >
+        test -f /models/${LLAMA_FAST_MODEL_FILE:-Qwen3-4B-Instruct-2507-UD-Q8_K_XL.gguf} &&
+        echo "already downloaded, skipping" ||
+        curl -L --fail --create-dirs -o /models/${LLAMA_FAST_MODEL_FILE:-Qwen3-4B-Instruct-2507-UD-Q8_K_XL.gguf}
+        https://huggingface.co/unsloth/Qwen3-4B-Instruct-2507-GGUF/resolve/main/${LLAMA_FAST_MODEL_FILE:-Qwen3-4B-Instruct-2507-UD-Q8_K_XL.gguf}
+
   # Local image generation — see issue #38 (wayfinder map). yurisasc's image
   # is gfx1201-tuned specifically (R9700's arch), unlike the official/AMD
   # ComfyUI image which doesn't pin RDNA4 support — see
@@ -118,6 +174,8 @@ services:
     depends_on:
       llama-server:
         condition: service_started
+      llama-server-fast:
+        condition: service_started
     volumes:
       - omniroute-data:/app/data
     env_file: .env