refactor(skill): rename validate → web-validate

Clearer scoped name for the W3C + WCAG skill. Updated: folder (git mv),
frontmatter name, H1 title, command refs, CLAUDE.md routing, 6 profiles
(functional — activate the skill by folder name), cross-refs in
harden/seo/depth-matrix/client-handover, agent dispatch refs, README +
USAGE tables.

Confidentiality: the client-deliverable leak-guard regex
(client-handover-writer.md) now matches BOTH /web-validate and legacy
/validate, so older client docs stay covered.

Left intentionally: validator-analyzer agent name (lockstep with
subagent_type + registry), .validate-cache/ + VALIDATE.md (audit-file
family {SEO,GEO,HARDEN,CSO,VALIDATE}.md), .claude/ history (append-only),
CHANGELOG old entry (added a new "renamed" entry instead). NL trigger
keywords kept so "validate" still routes here. Third-party html-validate
untouched.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01W9sqAwZxBMZSynZoVrEJhd

README.md

@@ -112,7 +112,7 @@ Versions are pinned in `plugins.lock.json`. To update: edit the file, then re-ru
 | `/pdf-translate` | Translate a PDF to another language, output as HTML (via Vision) |
 | `/close` | End-of-session ritual — alias for `/capitalize --ritual` (dedup + TODO reconcile + 3-question reflection) |
 | `/harden` | Web hardening audit — HTTPS/TLS, HSTS, CSP, security headers |
-| `/validate` | W3C HTML/CSS validity + WCAG 2.1 accessibility audit |
+| `/web-validate` | W3C HTML/CSS validity + WCAG 2.1 accessibility audit |
 | `/geo` | GEO-only audit — AI-search visibility (ChatGPT, Perplexity, Claude, Gemini…) |
 | `/client-handover` | Final project delivery — audits + branded deliverable (Markdown / HTML / PDF) |
 | `/profile` | Activate a skill profile (design / dev / qa / audit / minimal) |