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/references/create.md

@@ -101,8 +101,10 @@ plain sentence and `disable-model-invocation: true` instead.
 - `license` — include when distributing the skill externally
 - `compatibility` — include if the skill requires specific tools, runtimes, or network access
   (max 500 characters)
-- `metadata` — key-value map; use `author`, `version`, `category`; add `source_keys` now (Step 6)
-  if research sources are in context
+- `metadata` — key-value map. `version` is **required** on every skill (ADR-0022), seeded at
+  `"1.0.0"` for a retrofitted skill with no prior version and at `"0.1.0"` for a newly created
+  skill; `author` and `category` stay optional; add `source_keys` now (Step 6) if research sources
+  are in context
 - `allowed-tools` — space-separated pre-approved tools; reduces permission prompts (experimental —
   support varies by client)
 - `disable-model-invocation` — hand-invoked skills only