Add LLM compose stack for phy-srv-gpu01 (not deployed yet)

Follows the homelab pattern: ironicbadger.docker_compose_generator v2
renders services/<host>/NN-<stack>/compose.yml templates into
~/docker/compose.yaml on the host.

- 01-vllm: chat model, fixed --gpu-memory-utilization
- 02-embeddings: second vLLM instance (--task embed) rather than a
  separate toolchain, so SM120 support only has to be solved once
- 03-openwebui: Open WebUI + pgvector (not chroma — corpus size)
- 99-network: shared bridge; leading comment keeps networks: top-level
- pin docker_compose_generator to 2.0.1 — galaxy tags mix v1/v2 formats
- group_vars: stack config incl. LDAP placeholders still to be filled

The role only writes the compose file; starting the stack stays manual.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

ansible/group_vars/phy_srv_gpu01.yml

@@ -1,2 +1,41 @@
 ---
+# overrides of group_vars/all.yml
 
+hostname: phy-srv-gpu01
+
+# geerlingguy.docker
+docker_users:
+  - "{{ main_username }}"
+
+# ironicbadger.docker_compose_generator
+# services/<docker_compose_hostname>/NN-<stack>/compose.yml next to run.yml
+appdata_path: "/home/{{ main_username }}/appdata"
+docker_compose_generator_output_path: "/home/{{ main_username }}/docker/"
+docker_compose_hostname: phy-srv-gpu01
+docker_compose_generator_uid: "{{ main_uid }}"
+docker_compose_generator_gid: "{{ main_gid }}"
+
+# --- LLM stack -------------------------------------------------------------
+llm_dns_name: chat.phytron.local
+
+# ⚠️ TODO: pin to a build verified on SM120 (Blackwell) before the first deploy
+vllm_image: vllm/vllm-openai:latest
+vllm_model: Qwen/Qwen3-32B-FP8
+vllm_served_model_name: qwen3-32b
+vllm_gpu_memory_utilization: "0.80"
+vllm_max_model_len: "32768"
+
+embedding_model: BAAI/bge-m3
+embedding_model_name: bge-m3
+embeddings_gpu_memory_utilization: "0.10"
+
+openwebui_image: ghcr.io/open-webui/open-webui:main
+pgvector_image: pgvector/pgvector:pg16
+
+# --- AD/LDAP ---------------------------------------------------------------
+# ⚠️ TODO: real bind DN / base DN from the customer; group llm_users is agreed
+ldap_server_host: dc.phytron.local
+ldap_server_port: "389"
+ldap_bind_dn: "CN=svc-llm,OU=Service,DC=phytron,DC=local"
+ldap_search_base: "DC=phytron,DC=local"
+ldap_search_filter: "(&(objectClass=user)(memberOf=CN=llm_users,OU=Groups,DC=phytron,DC=local))"