feat(seo-skills): multi-backend Data Source Selection (#7)

Replaces single-vendor (Ahrefs-only) tool defaults with a per-task
backend menu across all 14 SEO skills. Each skill now lists every
capable MCP in allowed-tools and documents how to pick between
Semrush, Ahrefs, OurSEO Agent (CLI + MCP), DataForSEO, and GSC
in its SKILL.md Data Source Selection section.

Tool stubs (~40 new files) populated per skill with capability
deltas, call patterns, and explicit "not for this skill when"
callouts so the menu is self-correcting.

Skills affected: 19-keyword-strategy, 20-serp-analysis,
21-position-tracking, 22-link-building, 23-content-strategy,
24-ecommerce, 25-kpi-framework, 26-international, 27-ai-visibility,
28-knowledge-graph, 31-competitor-intel, 32-crawl-budget,
33-migration-planner, 34-reporting-dashboard.

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

custom-skills/24-seo-ecommerce/desktop/tools/ahrefs.md

@@ -1,15 +1,30 @@
-# Ahrefs
+# Ahrefs MCP
 
-> TODO: Document tool usage for this skill
+Use for **product/category backlinks** and third-party **site audit** views on e-commerce sites. Namespace: `mcp__ahrefs__*` / `mcp__claude_ai_Ahrefs__*`.
 
-## Available Commands
+## Key endpoints
 
-- [ ] List commands
+- `site-explorer-top-pages` — which product/category pages earn the most links/traffic
+- `site-explorer-pages-by-backlinks` — link equity distribution across the catalog
+- `site-audit-issues` — schema, canonical, parameter-URL issues from Ahrefs' crawler
+- `site-audit-page-explorer` — per-page issue surfacing
+- `keywords-explorer-overview` — product-term volume / KD
 
-## Configuration
+## Example
 
-- [ ] Add configuration details
+```
+mcp__ahrefs__site-explorer-top-pages(target="<store>", country="us", limit=100)
+mcp__ahrefs__site-audit-issues(project_id="<id>")
+mcp__ahrefs__keywords-explorer-overview(keyword="<product>", country="us")
+```
 
-## Examples
+## Strengths for this skill
 
-- [ ] Add usage examples
+- Surfaces which **product pages** earn external links — informs which products deserve hero-page promotion.
+- Site Audit catches canonical / parameter-URL issues across the catalog without running your own crawler.
+
+## Not for this skill when
+
+- **Product schema validation** — OurSEO `audit_page` + `build kg-schema` owns this end-to-end.
+- **Korean marketplace presence** (Naver Smart Store, Coupang, Gmarket, 11번가) — Ahrefs doesn't cover these. Use WebSearch.
+- **Live catalog crawl of the target** — OurSEO `crawl_website` is more configurable.

custom-skills/24-seo-ecommerce/desktop/tools/ourseo.md

@@ -0,0 +1,44 @@
+# OurSEO Agent (CLI + MCP)
+
+**Default** for e-commerce crawl, product schema validation, category taxonomy audit, duplicate/canonical detection, and the schema-fix path. Only backend that owns the catalog audit → fix workflow end-to-end.
+
+## CLI commands (Claude Code)
+
+```bash
+# Crawl the catalog
+our collect crawl https://<store> --max-pages 500
+our collect distributed https://<store> --workers 8 --max-pages 50000
+
+# Technical + schema audit
+our audit tech https://<store>
+our analyze mysql-batch --session <id> --export missing-schema --format excel
+
+# Build / fix Product schema
+our build kg-schema --type Product --name "<product>" --url <product-url> --auto-sameas
+our fix entity-schema --site https://<store> --type Product --entity-name "<product>" --cms <ghost|wordpress|strapi> --deploy
+
+# Korean batch keyword work
+our keywords ideas "<product>" --location 2410 --limit 50
+our serp ranked-keywords <store> --location 2410 --limit 100
+```
+
+## MCP tools (Claude Desktop)
+
+```
+mcp__ourseo__crawl_website(url="<store>", max_pages=500)
+mcp__ourseo__audit_page(url="<product-url>", audit_type="schema")
+mcp__ourseo__audit_page(url="<product-url>", audit_type="tech")
+```
+
+## Strengths for this skill
+
+- **Schema validation + deploy** — Product, Offer, AggregateRating, Review, BreadcrumbList. Validates AND can fix via CMS adapters.
+- **Canonical + duplicate detection** — built into the crawl + audit stage.
+- **Korean market batch** — `--location 2410` covers Korean e-commerce keyword work cheaply.
+- **Distributed crawler** scales to multi-tenant catalog audits.
+
+## Not for this skill when
+
+- **Competitor organic research** — Semrush `organic_research` is cleaner.
+- **Product/category backlink analysis** — Ahrefs `site-explorer-top-pages` + backlinks.
+- **Korean marketplace presence detection** — WebSearch (Naver Smart Store, Coupang, Gmarket, 11번가).

custom-skills/24-seo-ecommerce/desktop/tools/semrush.md

@@ -0,0 +1,34 @@
+# Semrush MCP
+
+Use for **e-commerce keyword discovery**, **organic competitor research**, and **third-party site audit** of stores.
+
+Call pattern: discovery → `get_report_schema` → `execute_report`.
+
+## Key reports
+
+- `keyword_research` — product / category term volume + KD + intent
+- `organic_research` — competitor store organic keywords + top pages
+- `overview_research` — store-level traffic / visibility
+- `siteaudit_research` — store-wide technical SEO audit
+
+## Example
+
+```
+mcp__semrush__keyword_research(query="<product term>", database="us")
+mcp__semrush__organic_research(query="<competitor store>", database="us")
+mcp__semrush__siteaudit_research(query="<your store>", database="us")
+```
+
+Korean market: `database="kr"`.
+
+## Strengths for this skill
+
+- Cleanest competitor-store organic view (which product terms drive their traffic).
+- Site audit catches site-wide technical issues quickly.
+- `keyword_research` is the default for product/category term expansion.
+
+## Not for this skill when
+
+- **Product schema validation** — OurSEO owns this.
+- **Korean marketplace presence** — WebSearch only.
+- **Catalog crawl with custom configuration** — OurSEO `crawl_website`.