Add SEO skills 19-28, 31-32 with full Python implementations

12 new skills: Keyword Strategy, SERP Analysis, Position Tracking,
Link Building, Content Strategy, E-Commerce SEO, KPI Framework,
International SEO, AI Visibility, Knowledge Graph, Competitor Intel,
and Crawl Budget. ~20K lines of Python across 25 domain scripts.
Updated skill 11 pipeline table and repo CLAUDE.md.
Enhanced skill 18 local SEO workflow from jamie.clinic audit.

Note: Skill 26 hreflang_validator.py pending (content filter block).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

custom-skills/32-seo-crawl-budget/desktop/tools/ahrefs.md

@@ -0,0 +1,17 @@
+# Ahrefs MCP Tools
+
+## site-explorer-pages-history
+
+Get historical page data for a domain to compare indexed pages with crawled pages.
+
+```
+mcp__ahrefs__site-explorer-pages-history
+```
+
+**Parameters**:
+- `target` (string, required): Domain or URL to analyze
+- `date_from` (string): Start date (YYYY-MM-DD)
+- `date_to` (string): End date (YYYY-MM-DD)
+- `mode` (string): "domain", "prefix", "exact", "subdomains"
+
+**Use case**: Compare Ahrefs indexed page counts with server log crawl data to identify indexing gaps and crawl budget inefficiencies.