Keep template-only lines out of the skills that ship #103

Some engineering skills that ship in generated solutions still talk about the template repository. packages-and-dependencies mentions Dependabot pull requests, but dependabot.yml doesn't ship, and it says to update "all five templates". A coding agent in someone's solution will follow those lines.

Phase 1: Clean up what ships

• Find every shipped skill line that only applies to the template repository
• Hide them in generated solutions the same way AGENTS.md does, or move them to a maintainer skill
• Add a Verify Template check that a generated solution's skills don't say "five templates" or "Dependabot"

Checks: Verify Template passes in all five, and the drift check stays green.