feat: add qdrant and neo4j for RAG vector/graph storage

Adds the two databases as infra services (own volume, ai-stack
network, host-published UI ports like comfyui) for an upcoming RAG
pipeline. Extraction/chunking/orchestration code is out of scope for
this repo — it's app logic that calls into these DBs and llama-server,
not compose infra.

Neo4j password follows the omniroute secret pattern: blank in
.env.example, auto-generated by scripts/update.sh.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DjhxWirQepKFEQj1huXNJR

.env.example

@@ -141,3 +141,8 @@ LLAMA_FAST_PARALLEL=1
 COMFYUI_DIFFUSION_MODEL_FILE=qwen_image_fp8_e4m3fn.safetensors
 COMFYUI_TEXT_ENCODER_FILE=qwen_2.5_vl_7b_fp8_scaled.safetensors
 COMFYUI_VAE_FILE=qwen_image_vae.safetensors
+
+# --- RAG databases (qdrant + neo4j, see wayfinder notes) ---
+# No auth on qdrant (its default) — same trust boundary as llama-server:
+# ai-stack is not exposed off-box. Random, filled in automatically:
+NEO4J_PASSWORD=