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

Makefile

@@ -0,0 +1,19 @@
+.PHONY: install project test update
+
+# Install the skills globally into $HOME (.agents/skills + .claude/skills).
+install:
+	@TARGET="$(HOME)" bash scripts/install.sh
+
+# Copy the skills into a project: make project TARGET=/path/to/repo
+project:
+	@test -n "$(TARGET)" || { echo "usage: make project TARGET=/path/to/repo"; exit 2; }
+	@TARGET="$(TARGET)" bash scripts/install.sh
+
+# Validate skills-lock.json and shellcheck the scripts.
+test:
+	@python3 -m unittest discover -s tests -v
+	@if command -v shellcheck >/dev/null; then shellcheck scripts/*.sh; else echo "shellcheck not installed - skipped"; fi
+
+# Update all skills to their latest versions and refresh skills-lock.json.
+update:
+	@bash scripts/update.sh