fix(skills): make all skills load-valid + add scripts/verify_skills.py

Add a comprehensive load verifier and fix the two issues it found:

- scripts/verify_skills.py: validates every loadable unit (flat root, suite sub-skill,
  plugin skill) with real YAML parsing, name regex + global uniqueness, frontmatter
  <=1024, description sanity, plugin.json JSON validity, and orphan detection. Read-only.
- 92-tui-design-template (root + code/SKILL.md): fix invalid YAML `triggers:` block
  (`- "a", "b"` multi-scalar list items) -> one phrase per list item.
- 17-seo-schema-generator: remove ">" from description ("generate -> validate" ->
  "generate then validate"); angle brackets are disallowed in descriptions.

Result: 75/75 loadable skills valid — 0 failures, 0 name collisions, 0 orphans,
0 plugin-manifest errors (65 flat + 3 plugins + 7 suite sub-skills).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

custom-skills/92-tui-design-template/code/SKILL.md

@@ -3,10 +3,18 @@ name: tui-design-template
 description: Build Norton Commander / Gopher style TUI wizard interfaces for CLI tools using Python Rich. Covers architecture, components, keyboard input, bilingual i18n, and battle-tested gotchas.
 version: 1.0.0
 triggers:
-  - "build TUI", "TUI wizard", "terminal UI", "CLI wizard"
-  - "Norton Commander style", "Gopher style", "retro TUI"
-  - "Rich TUI", "interactive CLI", "keyboard navigation"
-  - "dual panel interface", "terminal wizard"
+  - build TUI
+  - TUI wizard
+  - terminal UI
+  - CLI wizard
+  - Norton Commander style
+  - Gopher style
+  - retro TUI
+  - Rich TUI
+  - interactive CLI
+  - keyboard navigation
+  - dual panel interface
+  - terminal wizard
 tools:
   - Read
   - Write