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

plugins/lint/skills/vale-config/SKILL.md

@@ -22,6 +22,7 @@ metadata:
 - Installing the `vale` binary installs no styles. A fresh `.vale.ini` with `BasedOnStyles` set will fail or find nothing until `vale sync` runs and downloads the `Packages` it declares.
 - `.vale.ini` is order-sensitive: global (core) settings first, then the optional `[formats]` section, then glob sections (`[*]`, `[*.md]`, …). Settings in a glob section only apply to files matching that glob.
 - `Packages` (top-level, fetched by `vale sync`) and `BasedOnStyles` (per-glob, activates) are separate keys — a style only lints files once it's in both. This is the step people forget.
+- A rule scoped to `text.frontmatter.<key>` (e.g. `text.frontmatter.description`) only reliably matches when that field's value is a single physical line. If it's a YAML block scalar (`>`/`|`) spanning 2+ physical lines, the scope silently stops matching — no error, just 0 findings — confirmed against Vale 3.15.2. Verify with a deliberately-bad multi-line fixture before trusting a frontmatter-scoped rule in production; if the field is commonly authored as a multi-line block scalar, flatten it to one line ahead of the `vale` call rather than relying on the scope alone.
 
 ## Setup workflow