Author docker-compose stack: llama.cpp (ROCm) + Open WebUI + Qdrant + Lazytainer

Resolves wayfinder ticket #4. Wires up the locked decisions from the map:
- llama.cpp (ghcr.io/ggml-org/llama.cpp:server-rocm, gfx1201) serving
  Qwen3.8-27B-UD-Q4_K_XL.gguf, port published for direct Claude Code CLI /
  Kimi CLI access alongside Open WebUI.
- Open WebUI with WEBUI_AUTH on, RAG+Memory wired to a standalone Qdrant
  service.
- Lazytainer labels on llama-server for a 15 min idle-stop.
- Named Docker volumes only (models, qdrant-data, openwebui-data) — no host
  bind-mounts.
- One-off 'downloader' compose profile instead of a host-side script with
  its own dependencies, wrapped by scripts/download-model.sh.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.env.example

@@ -0,0 +1,21 @@
+# Copy to .env and adjust. All values below are defaults baked into
+# docker-compose.yml — only uncomment/change what you actually want to override.
+
+# --- llama.cpp / model ---
+LLAMA_MODEL_FILE=Qwen3.8-27B-UD-Q4_K_XL.gguf
+LLAMA_GPU_LAYERS=999
+# 65536 (64K) fits comfortably in 32GB VRAM alongside the model weights.
+# Raise toward 131072 if you need more context; see docs/research/qwen3.8-27b-quant.md
+# for the VRAM math at larger context sizes.
+LLAMA_CTX_SIZE=65536
+LLAMA_PORT=8080
+
+# --- Open WebUI ---
+WEBUI_PORT=3000
+# Dummy key — llama.cpp's OpenAI-compatible endpoint doesn't check it, but
+# Open WebUI requires the field to be non-empty.
+OPENAI_API_KEY=local
+
+# --- Lazytainer ---
+# Seconds of inactivity before llama-server is stopped. 900 = 15 min.
+LAZYTAINER_INACTIVE_TIMEOUT=900