docs: trim skill READMEs and ADR/changelog narration

Two related simplification-audit findings, bundled because they edit
some of the same skill-audit files and splitting would fragment
single-file diffs.

Finding 10: delete 48 per-skill/reference README.md files (they
restated SKILL.md in narrative form and no agent ever loads them) plus
2 scaffold templates. Drop the README criterion from skill-audit's
file-structure.md and finding-criteria.md, and the README-generation
step from skill-author's new-skill.sh; update new-skill.bats to match.
Plugin-root READMEs are kept intentionally, out of scope.

Finding 12: strip historical ADR-0020/ADR-0023 citations and
changelog-style narration from model-facing skill content across
kyberforge and git plugin skills. Delete skill-author's one-time
retrofit.md migration guide and its references. Some ADR-0023 tags
were not narration but check-rtk-prefix's required opt-out marker for
intentionally-bare git commands -- those were restored, not stripped.

Mirror re-synced and full pre-commit/pre-push suite verified green.

Refs: SIMPLIFICATION-AUDIT.md findings 10, 12

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YR2CjVumUbEGWcMikcoXBD

plugins/git/skills/pc-author/README.md

@@ -1,26 +0,0 @@
-# pc-author
-
-Create, add, remove, update, and configure `.pre-commit-config.yaml`.
-
-## What it does
-
-Manages the pre-commit configuration file in any git repo. When invoked, it scans the repo for languages, proposes appropriate hooks with rationale, and writes or modifies `.pre-commit-config.yaml`. It validates every write with `pre-commit validate-config` and flags stale revision pins. It does not run hooks or install them into `.git/hooks/` — use `pc-run` for that.
-
-## Usage
-
-```
-/pc-author
-```
-
-Invoke with no arguments. The skill determines from context whether to create a new config or modify an existing one.
-
-## Files
-
-| File | Purpose |
-|------|---------|
-| `SKILL.md` | Skill instructions for agents |
-| `references/create-config.md` | Loaded when the repo has no `.pre-commit-config.yaml` — the create-from-scratch flow |
-| `references/modify-config.md` | Loaded when a `.pre-commit-config.yaml` already exists — add, remove, top-level keys, rev staleness |
-| `references/hooks-by-language.md` | Hook recommendations by detected language/extension |
-| `references/README.md` | Index of files in references/ |
-| `references/sources.md` | Provenance — research sources that informed this skill |

plugins/git/skills/pc-author/references/README.md

@@ -1,16 +0,0 @@
----
-source_keys:
-  - context7-pre-commit-com
-  - pre-commit-com
-  - context7-pre-commit-hooks
-  - pre-commit-hooks-github
----
-
-# references/
-
-| File | Purpose |
-|---|---|
-| `create-config.md` | The create flow — read when the repo has no `.pre-commit-config.yaml` |
-| `modify-config.md` | The modify flow — read when a `.pre-commit-config.yaml` already exists |
-| `hooks-by-language.md` | Hook recommendations by language/context — repo, rev, and rationale for adding hooks |
-| `sources.md` | Provenance: research sources that informed this skill |