fix(lint): flatten multi-line frontmatter descriptions before Vale runs

Vale's text.frontmatter.description scope silently stops matching once
the description is a YAML block scalar spanning 2+ physical lines —
the style used by most skills/agents in this repo. scripts/vale-wrap.sh
flattens the description to one line in a scratch copy (preserving the
repo-relative path and total line count) before invoking real vale, and
both audit skills plus the pre-commit hook now call it instead of vale
directly. Also tightens the pre-commit hook's file glob to single path
segments so it can't cross into docs/research examples or asset
templates the way the audit skills' scoped invocations already avoid.

Addresses PR #85 review feedback.

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

.pre-commit-config.yaml

@@ -102,9 +102,9 @@ repos:
         stages: ['pre-commit']
         name: Vale audit prefilter
         description: Run Vale against skill/agent markdown files as a deterministic prefilter for skill-audit/agent-audit
-        entry: vale --config .vale.ini
-        language: unsupported
-        files: '^plugins/.*/(skills/.*/SKILL\.md|agents/.*\.md)$'
+        entry: scripts/vale-wrap.sh --config .vale.ini
+        language: script
+        files: '^plugins/[^/]+/(skills/[^/]+/SKILL\.md|agents/[^/]+\.md)$'
         pass_filenames: true
 
   - repo: meta