feat(kyberforge): add plugin-author and marketplace-author skills

## Why

Plugin and marketplace management had no governed authoring path. Creating or
updating a plugin required knowing the dual-manifest convention, version parity
rules, and directory skeleton by memory — nothing enforced consistency or guided
the process.

`/plugin-author` closes that gap by owning the full plugin scaffold lifecycle:
create, update, rename, and release. `/marketplace-author` handles the
marketplace-facing side: register, deregister, and update plugin entries in
`marketplace.json`.

ADR-0016 codifies the version parity convention (identical `version` in both
`plugin.json` and `.claude-plugin/plugin.json`) that `/plugin-author` now
enforces. The two plugin.json files in this repo are backfilled to comply
(keys also sorted to pass the pretty-format-json hook). CONTEXT.md gains
glossary entries for "plugin scaffold" and "version parity" so future agents
have shared vocabulary for these concepts.

## Implementation Notes

`/plugin-author` ships a `scripts/new-plugin.sh` scaffold script that generates
the directory skeleton and both manifests in one shot; the skill calls the script
rather than generating files ad hoc so the scaffold is reviewable and repeatable.

Version parity is an invariant, not a suggestion — the skill will fail loudly
on create/update if the two versions would diverge.

ADR: docs/adr/0016-plugin-version-parity.md

plugins/kyberforge/skills/marketplace-author/tests/README.md

@@ -0,0 +1,29 @@
+# tests/
+
+Test files for scripts bundled with this skill.
+
+## When to add tests
+
+Add tests here when the skill has scripts in `scripts/` that are complex enough
+to break silently — validators, parsers, generators, anything with branching
+logic or edge cases. Test infrastructure (`.bats`, `*_test.*`, `test_*.sh`)
+belongs here, not in `scripts/`.
+
+## Current state
+
+`marketplace-author` has no `scripts/` directory — all operations are performed
+directly by the agent using Read/Edit/Write tools. No test infrastructure is
+needed.
+
+If a script is added in the future, add bats tests here. Dependencies:
+
+```bash
+git clone https://github.com/bats-core/bats-support tests/test_helper/bats-support
+git clone https://github.com/bats-core/bats-assert tests/test_helper/bats-assert
+```
+
+Run tests from the repo root:
+
+```bash
+bats plugins/kyberforge/skills/marketplace-author/tests/
+```