Stand up open-webui on dankclaw (quadlet, boot-persistent)

Replace the dead dankserver open-webui (bare container, :3000, pointed at a
dead :9090 backend) with a boot-persistent quadlet on dankclaw:
- CPU image (:main); dankclaw is CPU-only, so the :cuda image is wasted.
- Isolated on slirp4netns; publishes 3005 (3000 is Gitea's HTTP port).
- Default LLM backend is the local vLLM on 52625 (frank-default-large).
- Data persists under /home/dank/Containers/open-webui/data.
- Caddy route now proxies to the published LAN port (the container is not on
  Caddy's network).

Also corrects the model/port mapping in the docs: the live state (verified
2026-08-19) is frank-default-large on vLLM :52625 (dankclaw) and
frank-default-small on llama.cpp :7770 (dankserver) — the reverse of the
2026-08-17 note.

tests/open_webui_quadlet.bats

@@ -0,0 +1,62 @@
+#!/usr/bin/env bats
+# Seam: open-webui on dankclaw, boot-persistent via Quadlet.
+#
+# The old open-webui was a bare container on dankserver (port 3000) pointing at a
+# dead LLM backend (:9090). This unit stands one up on dankclaw on a free port
+# (3005), on the CPU image (dankclaw is CPU-only), wired to the live vLLM
+# backend (host.containers.internal:52625, model frank-default-large).
+
+load helpers
+
+QDIR="$REPO_ROOT/dankclaw/open-webui/quadlet"
+
+@test "the open-webui quadlet file exists" {
+    [ -f "$QDIR/open-webui.container" ]
+}
+
+@test "open-webui uses the CPU image, not :cuda (dankclaw is CPU-only)" {
+    grep -qE '^Image=ghcr\.io/open-webui/open-webui:main$' "$QDIR/open-webui.container" \
+        || { echo "open-webui.container must use the :main (CPU) image"; return 1; }
+    if grep -qE '^Image=.*:cuda' "$QDIR/open-webui.container"; then
+        echo "open-webui.container must not use the :cuda image on a CPU-only host"
+        return 1
+    fi
+    return 0
+}
+
+@test "open-webui is isolated on slirp4netns" {
+    grep -qE '^Network=slirp4netns' "$QDIR/open-webui.container" \
+        || { echo "open-webui.container must set Network=slirp4netns"; return 1; }
+}
+
+@test "open-webui publishes 3005:8080 (a free port; 3000 is Gitea)" {
+    grep -qE '^PublishPort=3005:8080' "$QDIR/open-webui.container" \
+        || { echo "open-webui.container must publish 3005:8080"; return 1; }
+}
+
+@test "open-webui points its LLM at the live vLLM backend (52625)" {
+    grep -qE '^Environment=OPENAI_API_BASE_URL=http://host\.containers\.internal:52625' \
+        "$QDIR/open-webui.container" \
+        || { echo "open-webui.container must set OPENAI_API_BASE_URL to the vLLM on 52625"; return 1; }
+}
+
+@test "open-webui persists its data under /home/dank/Containers/open-webui/data" {
+    grep -qE '^Volume=/home/dank/Containers/open-webui/data:/app/backend/data' \
+        "$QDIR/open-webui.container" \
+        || { echo "open-webui.container must mount the data dir at /app/backend/data"; return 1; }
+}
+
+@test "open-webui is installed for boot (WantedBy=default.target)" {
+    grep -qE '^WantedBy=default\.target' "$QDIR/open-webui.container" \
+        || { echo "open-webui.container: [Install] must set WantedBy=default.target"; return 1; }
+}
+
+@test "no secret material in the quadlet file" {
+    # The LLM backend is a local LAN endpoint; no key is required. No 44-char
+    # base64 secret-like value may appear in the tracked file.
+    if grep -qE '[A-Za-z0-9+/]{44}=' "$QDIR/open-webui.container"; then
+        echo "open-webui.container: contains a secret-like value"
+        return 1
+    fi
+    has_no_leaked_secret "$QDIR/open-webui.container"
+}