Tag releases as mattpocock-skills--v{version} so plugin dependencies can pin a version

## Request Push git tags of the form `mattpocock-skills--v{version}` for each release (for example `mattpocock-skills--v1.2.3`), in addition to the current `v1.2.3` tags. `claude plugin tag --push` creates them from `.claude-plugin/plugin.json`. ## Why Claude Code lets a plugin declare another plugin as a dependency with a semver constraint, for example `{ "name": "mattpocock-skills", "marketplace": "claude-plugins-official", "version": "=1.2.3" }`. Claude Code resolves that constraint against git tags named `{plugin-name}--v{version}` on the dependency's repository, per [Constrain plugin dependency versions](https://code.claude.com/docs/en/plugin-dependencies). The repository currently has `v1.2.3` and one `mattpocock-skills@1.0.0`, and neither form matches, so any constraint on this plugin fails the install with `no-matching-tag`. A downstream plugin whose skills build on this collection (invoking `/tdd`, `/code-review`, `/domain-modeling`, and others) wants to hold a tested version until it adapts to a breaking release. Without the tag convention, the only option is an unconstrained dependency that moves whenever the official marketplace entry updates. ## Context Claude Code docs: https://code.claude.com/docs/en/plugin-dependencies#tag-plugin-releases-for-version-resolution