feat(kyberforge): wire Vale as deterministic prefilter for skill-audit/agent-audit

Adds repo-root .vale.ini plus a custom Kyberforge style (description-opener,
vague-wording, and generic reference-pointer padding rules) and a
KyberforgeCopilot style scoped to .agent.md files (Use proactively check).
skill-audit and agent-audit Step 1 now run vale against the specific file(s)
being audited and defer the corresponding Description/Patterns/Body checks
to its output instead of re-deriving them by LLM judgment, per the split
proposed in issue #84.

Closes #84

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FxG5T8EJDgkABXxuneuFfn

styles/KyberforgeCopilot/ProactivePhrase.yml

@@ -0,0 +1,7 @@
+extends: existence
+message: "'%s' is CC-specific phrasing with no effect in Copilot descriptions — remove it"
+level: warning
+scope: text.frontmatter.description
+ignorecase: true
+tokens:
+  - Use proactively