feat: reproducible agent skill collection with install/update tooling

- skills-lock.json pins every skill (extracted from infinito-nexus-core)
- make install (global to $HOME) and make project TARGET=<repo> copy the
  rendered skills into .agents/skills + .claude/skills
- make update refreshes the lock via npx skills; make test validates the
  lock shape and shellchecks the scripts
- CI: test workflow on push/PR, daily update workflow opening a PR
- MIRRORS for code.infinito.nexus and git.veen.world

.github/workflows/test.yml

@@ -0,0 +1,16 @@
+name: 🧪 Test
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  test:
+    name: 🧪 Lock + scripts
+    runs-on: ubuntu-latest
+    steps:
+      - name: ⬇️ Checkout
+        uses: actions/checkout@v7
+
+      - name: 🧪 Run tests
+        run: make test