chore(make): drop disable-model-invocation from the new-skill template

BDR-019 stripped the key from all 27 skills because `true` blocks model AND
orchestrator routing — silently breaking the routing CLAUDE.md describes —
while `false` was a no-op noise line. The scaffold kept injecting `true`, so
every skill created with `make new-skill` would have shipped unroutable.

doctor.sh already covers the other half upstream: its check was inverted to
warn on REINTRODUCTION rather than on absence, which is what surfaced this —
a new skill from the template would now trip that very guard.

Makefile

@@ -71,7 +71,7 @@ new-skill: ## Create a new skill scaffold (usage: make new-skill name=myskill)
 		echo "✅ Created agents/$(name).md"; \
 	else echo "⚠️  agents/$(name).md already exists"; fi
 	@if [ ! -f skills/$(name)/SKILL.md ]; then \
-		printf -- '---\nname: $(name)\ndescription: <what this skill does — front-load key use case, max 250 chars>\nargument-hint: <what to pass>\ndisable-model-invocation: true\nallowed-tools: Read, Grep, Glob, Bash\n---\n\nLoad and follow strictly:\n- .claude/agents/$(name).md\n\nExecute on:\n\n$$ARGUMENTS\n' > skills/$(name)/SKILL.md; \
+		printf -- '---\nname: $(name)\ndescription: <what this skill does — front-load key use case, max 250 chars>\nargument-hint: <what to pass>\nallowed-tools: Read, Grep, Glob, Bash\n---\n\nLoad and follow strictly:\n- .claude/agents/$(name).md\n\nExecute on:\n\n$$ARGUMENTS\n' > skills/$(name)/SKILL.md; \
 		echo "✅ Created skills/$(name)/SKILL.md"; \
 	else echo "⚠️  skills/$(name)/SKILL.md already exists"; fi
 	@echo "   Edit both files, then run: bash link.sh"