feat(kyberforge): improve skill-author — duality description, source_keys guidance, pre-audit checklists, version bump conventions

- references/sources.md: add YAML frontmatter with source_keys to fix provenance chain break
- SKILL.md description: make create/improve duality explicit ("Handles both the full create flow ... and the improve flow ...")
- SKILL.md Step 2: add inline metadata.source_keys instruction — fill early, not deferred to Step 5
- SKILL.md Step 6 (create) / Step 5 (improve): add pre-audit manual checklists and version bump conventions (minor for create, patch for improve)
- README.md: correct false claim that the skill bumps plugin manifests; it bumps metadata.version only

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0147vXtL5sP6vorDdqXGJJU9

plugins/kyberforge/skills/skill-author/README.md

@@ -4,7 +4,7 @@ Author and refine skills conforming to the [agentskills.io](https://agentskills.
 
 ## What it does
 
-Routes to one of two flows based on context: if no skill directory exists at the target path, it scaffolds the directory from annotated templates, fills in `SKILL.md` and supporting files, and validates the result. If an existing skill directory and improvement signals are both present, it groups those signals by root cause and applies targeted edits, then re-validates. In both flows, if the skill lives inside a plugin directory, bumps the plugin version in both manifests.
+Routes to one of two flows based on context: if no skill directory exists at the target path, it scaffolds the directory from annotated templates, fills in `SKILL.md` and supporting files, and validates the result. If an existing skill directory and improvement signals are both present, it groups those signals by root cause and applies targeted edits, then re-validates. In both flows, bumps the skill's `metadata.version` when present (minor for create, patch for improve).
 
 ## Before you start