chore(higgsfield): lock entry and gitignore for the skill pack

.gitignore

@@ -101,6 +101,11 @@ skills/darwin-skill
 # membership, so the pack can gain a skill with no edit here.
 skills/21st-*
 
+# Higgsfield skill pack symlinks — created on demand by toggle-external.sh
+# (`enable higgsfield` / `enable higgsfield-websites`). The pack is OFF by
+# default and in no profile, so these usually don't exist.
+skills/higgsfield-*
+
 # Context7 docs-lookup skill — installed by `ctx7 setup --claude --cli`
 # (install-plugins.sh Step 6, when absent) into ~/.claude/skills (a symlink to
 # this repo's skills/). ctx7-managed and re-created on demand — not vendored here.
@@ -236,6 +241,13 @@ skills-external/writing-skills/
 # layout and the content is sha256-verified against 21st.dev's manifest.
 skills-external/21st-*/
 
+# Higgsfield skill pack — machine-owned: a git clone of higgsfield-ai/skills,
+# staged by lib/higgsfield-skills.sh (install-plugins.sh Step 8.6) and moved
+# here, refreshed by update-all.sh. Not vendored: it tracks upstream main.
+# The second line is the helper's stage, left behind only by a killed run.
+skills-external/higgsfield-*/
+skills-external/.higgsfield-stage.*/
+
 # npx `skills add` project-scope artifacts — darwin-skill copies itself into
 # the repo's .agents/ and writes skills-lock.json at root. Our own agents live
 # in agents/ (no dot) and stay tracked. Anchored to root so only the dotted