refact(deployer): the LLM handlers gate through the shared library

deploy_llm_dragoon/zealot/arkon now call require_image / require_bytes /
require_min_mib / require_file / require_dir_files, so the deployer and the
serve scripts refuse the same missing payload with the same words — the
2026-10-01 crash-loop law, enforced by construction instead of by duplicated
shell. require_exec joins the library for the native-runtime gate (a
compiled tree that lost its +x refuses like a missing one). relink_unit
takes SYSTEMD_SYSTEM_DIR so a handler can be driven end to end in a sandbox.

The library's own refusals now carry their status: a bash function that
ends inside an if returns the CONDITION's status, so a gate whose last
statement is its refusal printed the message and returned SUCCESS — the
new seam caught it, and the gate tests pin it.

New seam tests/llm_deploy_gates.bash + tests/stubs/: deploy-remote.sh's LLM
handlers EXECUTED against stub systemctl/podman/sudo/ss/curl, asserting
exit status, refusal text, no restart, and the pending state marker.

scripts/serve-frank-dragoon.sh

@@ -79,10 +79,10 @@ require_bytes "$FRANK_DRAGOON_MODEL_DIR/$FRANK_DRAGOON_CHECKPOINT" \
     checkpoint "$FRANK_DRAGOON_CHECKPOINT_BYTES" \
     "fetch it: bash scripts/download-frank-dragoon-flashnext.sh" || exit 1
 require_bytes "$FRANK_DRAGOON_MODEL_DIR/$FRANK_DRAGOON_NGRAM_TABLE" \
-    n-gram-table "$FRANK_DRAGOON_NGRAM_BYTES" \
+    n-gram "$FRANK_DRAGOON_NGRAM_BYTES" \
     "fetch it: bash scripts/download-frank-dragoon-flashnext.sh" || exit 1
 require_bytes "$FRANK_DRAGOON_MODEL_DIR/$FRANK_DRAGOON_VISION_TOWER" \
-    vision-tower "$FRANK_DRAGOON_VISION_BYTES" \
+    vision "$FRANK_DRAGOON_VISION_BYTES" \
     "fetch it: bash scripts/download-frank-dragoon-flashnext.sh" || exit 1
 
 # The payload ships the tokenizer as a FLAT DIRECTORY. A HuggingFace cache