feat(stack): remove Open WebUI and Qdrant

No longer needed - every client is a coding CLI behind the OmniRoute
gateway, not a chat UI. Drops the open-webui and qdrant services,
WEBUI_PORT/OPENWEBUI_OMNIROUTE_KEY env vars, and the openwebui-data/
qdrant-data volumes. Qdrant only ever served Open WebUI's own built-in
memory/RAG (unrelated to the gateway-level knowledgebase removed in
472e3a4), so it goes too rather than sit unused.

Docs updated: README, docs/network-access.md (ai.home/ai.haylan.ch
section was entirely about Open WebUI, rewritten around the gateway),
docs/proxy-key-onboarding.md, docs/proxy-request-priority.md.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VPZ6TogJiYxG8E4EQBB197

.env.example

@@ -28,10 +28,6 @@ LLAMA_GPU_LAYERS=999
 # of dropping context: --cache-type-k/v q8_0 roughly halves it.
 LLAMA_CTX_SIZE=131072
 
-# --- Open WebUI ---
-WEBUI_PORT=8008
-# No scripted mint yet — set OPENWEBUI_OMNIROUTE_KEY below by hand instead.
-
 # --- Lazytainer ---
 # Seconds of inactivity before llama-server is stopped. 900 = 15 min.
 LAZYTAINER_INACTIVE_TIMEOUT=900
@@ -63,8 +59,8 @@ OMNIROUTE_STORAGE_ENCRYPTION_KEY=
 # Per-deployment salts — random is fine, just needs to be stable:
 OMNIROUTE_MACHINE_ID_SALT=
 OMNIROUTE_CLI_SALT=
-# Per-workload virtual keys — omniroute has no scripted /key/generate
-# equivalent yet (its key-creation endpoint needs a dashboard login session,
-# not a static bearer key — see issue #37), so mint these by hand in the
-# dashboard for now. See docs/proxy-key-onboarding.md.
-OPENWEBUI_OMNIROUTE_KEY=
+# Per-workload virtual keys (one per client that calls the gateway) have no
+# scripted /key/generate equivalent yet — omniroute's key-creation endpoint
+# needs a dashboard login session, not a static bearer key (see issue #37).
+# Mint them by hand in the dashboard, add a KEY=value line here per workload
+# as you onboard one. See docs/proxy-key-onboarding.md.