feat(agenthub): add AgentHub plugin with cross-domain examples, SEO optimization, and docs site fixes

- AgentHub: 13 files updated with non-engineering examples (content drafts,
  research, strategy) — engineering stays primary, cross-domain secondary
- AgentHub: 7 slash commands, 5 Python scripts, 3 references, 1 agent,
  dry_run.py validation (57 checks)
- Marketplace: agenthub entry added with cross-domain keywords, engineering
  POWERFUL updated (25→30), product (12→13), counts synced across all configs
- SEO: generate-docs.py now produces keyword-rich <title> tags and meta
  descriptions using SKILL.md frontmatter — "Claude Code Skills" in site_name
  propagates to all 276 HTML pages
- SEO: per-domain title suffixes (Agent Skill for Codex & OpenClaw, etc.),
  slug-as-title cleanup, domain label stripping from titles
- Broken links: 141→0 warnings — new rewrite_skill_internal_links() converts
  references/, scripts/, assets/ links to GitHub source URLs; skills/index.md
  phantom slugs fixed (6 marketing, 7 RA/QM)
- Counts synced: 204 skills, 266 tools, 382 refs, 16 agents, 17 commands,
  21 plugins — consistent across CLAUDE.md, README.md, docs/index.md,
  marketplace.json, getting-started.md, mkdocs.yml
- Platform sync: Codex 163 skills, Gemini 246 items, OpenClaw compatible

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

agents/personas/README.md

@@ -57,7 +57,7 @@ Both coexist. Use task agents for focused work, personas for ongoing collaborati
 
 ## Creating Your Own
 
-See [TEMPLATE.md](TEMPLATE.md) for the format specification. Key elements:
+See [TEMPLATE.md](template.md) for the format specification. Key elements:
 
 ```yaml
 ---

agents/project-management/cs-project-manager.md

@@ -496,7 +496,7 @@ echo "Template: ../../project-management/senior-pm/assets/executive_report_templ
 
 - [cs-product-manager](../product/cs-product-manager.md) -- Product prioritization with RICE, customer discovery, PRD development
 - [cs-agile-product-owner](../product/cs-agile-product-owner.md) -- User story generation, backlog management, acceptance criteria (planned)
-- [cs-scrum-master](cs-scrum-master.md) -- Dedicated Scrum ceremony facilitation and team coaching (planned)
+- cs-scrum-master -- Dedicated Scrum ceremony facilitation and team coaching (planned)
 
 ## References