feat(frank-dragoon): put the endpoint on the app bridge so app containers can name it

An endpoint on podman's rootless default (pasta) has no address another
container can use, measured on 2026-10-19 from inside open-notebook:

  - 192.168.0.143:7770            connection refused (pasta forwards the
                                  published port in the host netns; no netavark
                                  DNAT exists for traffic arriving from a
                                  rootless bridge)
  - host.containers.internal:7770 200, but the alias resolves to 169.254.1.2 —
                                  link-local, which open-notebook's URL guard
                                  refuses to store
  - frank-dragoon-halogen:8731    name unknown: different netns
  - --network pasta --network dankclaw_default
                                  "cannot set multiple networks without bridge
                                  network mode" — pasta cannot be added to

So reaching the NPU endpoints from an app container means moving the container
onto dankclaw_default (FRANK_DRAGOON_NETWORK; empty keeps today's shape). This
is not an exposure change: the engine's unauthenticated token port binds the
container's own loopback (/proc/net/tcp: 127.0.0.1:8730 against 0.0.0.0:8731),
so only the API port becomes name-resolvable — the same trust the published
7770 already carries on the LAN. The deployer refuses a network that does not
exist rather than starting a unit that restart-loops on it.

Co-Authored-By: omp <omp@dankclaw>

scripts/deploy-remote.sh

@@ -1348,6 +1348,7 @@ LLM_DRAGOON_NPU_MODELS="${LLM_DRAGOON_NPU_MODELS:-qwen3-embedding-0.6b}"
 LLM_DRAGOON_NPU_DIR="${LLM_DRAGOON_NPU_DIR:-/home/dank/models/halogen-npu}"
 LLM_DRAGOON_DEV_ACCEL="${LLM_DRAGOON_DEV_ACCEL:-/dev/accel/accel0}"
 LLM_DRAGOON_XRT_DIR="${LLM_DRAGOON_XRT_DIR:-/usr/lib/x86_64-linux-gnu}"
+LLM_DRAGOON_NETWORK="${LLM_DRAGOON_NETWORK:-dankclaw_default}"
 
 retire_halogen_dragoon_quadlet() {
     local trash="$HOME/.AGENTTRASH/20260919-orca-cutover/quadlet"
@@ -1426,6 +1427,14 @@ deploy_llm_dragoon() {
         fi
     done
 
+    # The container network has to exist before the run line names it (a typo
+    # there is a restart-looping unit, not a config error anyone reads).
+    if [[ -n "$LLM_DRAGOON_NETWORK" ]] && ! podman network exists "$LLM_DRAGOON_NETWORK"; then
+        echo "ERROR: podman network $LLM_DRAGOON_NETWORK does not exist" >&2
+        echo "frank-dragoon: create it or blank FRANK_DRAGOON_NETWORK (pasta default)" >&2
+        return 1
+    fi
+
     # --- NPU lane: the same three predicates the serve script checks ---------
     if [[ -n "$LLM_DRAGOON_NPU_MODELS" ]]; then
         if [[ ! -e "$LLM_DRAGOON_DEV_ACCEL" ]]; then