flake-templates

Use when the user wants to initialize Dependabot in a repository. Copy the bundled `assets/dependabot.yml` and `assets/auto-merge-dependabot.yml` into `.github`, keep only the package ecosystems and directories that actually exist in the repository, choose the appropriate Nix update strategy for each flake, adapt the auto-merge workflow to the repository's update command, refresh pinned action SHAs, validate with zizmor, and remind the user to create the required GitHub App secrets manually.