refactor(skills): mandate metadata.version on every skill's frontmatter

Only 12 of 39 skills carried metadata.version, and adoption tracked
which plugin a skill lived in rather than any stated rule: core,
gitea and lint were consistent adopters, bin and kyberforge were
consistent non-adopters, git was split with one outlier. There was
no documented convention, and skill-author's own bump logic was
already written as if presence were conditional.

metadata.version is now required on every skill. The 19 skills here
that never carried one (bin, kyberforge, gitea-files) are seeded at
1.0.0, not 0.1.0 -- that value stays reserved for a skill's actual
creation point under skill-author's existing convention. The
skill-frontmatter pre-commit hook now fails a SKILL.md missing the
field, the same class of failure as a missing name/description.

Full rationale in the new ADR. The git-plugin skills that also need
this field follow in the next commit, bundled with issue #113's rtk
normalization since both touch the same files.

Refs: #127
ADR: 0022
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EeH8SCbcrCAQrtymkNuhKP

plugins/kyberforge/.apm/skills/skill-author/SKILL.md

@@ -6,6 +6,7 @@ description: >
   Not read-only review -> `skill-audit`. Not agent files -> `agent-author`.
 allowed-tools: Bash Read Write Edit
 metadata:
+  version: "1.0.0"
   category: factory
   source_keys:
     - agentskills-home
@@ -56,6 +57,6 @@ Gates `/skill-audit` enforces in both flows:
 
 Run `/skill-audit` on the resolved skill directory; resolve every FAIL before reporting done. It checks name-to-directory match, placeholders, both size budgets, boundary-target resolution and script hygiene — do not hand-check those. Hand-check the one thing it misses: an empty body reports `PASS  SKILL.md body word count 0 (ADR-0020 target: 600)`, so confirm at least one non-empty section exists.
 
-With `metadata.version` present, bump the **minor** version on create (new skills start at `0.1.0`) and the **patch** version on improve.
+Bump `metadata.version`: the **minor** version on create (new skills start at `0.1.0`) and the **patch** version on improve.
 
 **Commit verification.** Inside a git worktree: once the audit is clean, run `git add` and `git commit` — do not stop at staging. Re-run `git log --oneline -1` and confirm the hash changed from Step 1's. A non-empty `git diff --stat` is not proof: staged-but-uncommitted work is part of no commit and is silently lost if the tree is cleaned up. Report done only once the hash has changed. Outside a worktree (a skill under `~/.claude/skills/`, say) nothing is committable — report done on a clean audit, naming that as the reason.