feat(seo): merge claude-seo into Synapse SEO skills + fix skills FTS …

[deve1993]

…sync

Two changes from incorporating the claude-seo repo (MIT, (c) 2026 agricidaniel):

SEO skills (content lives in the per-machine .opencode mirror, which is NOT git-tracked, so the merged set is vendored here under scripts/seed-seo-skills/ as the shareable record + a seeder to push it to any graph.db):

• 11 enriched: seo, seo-technical, seo-audit, seo-geo, seo-schema, seo-content, seo-hreflang, seo-images, seo-sitemap-advanced, seo-competitor-pages, seo-plan (added audit/E-E-A-T/GEO methodology, CWV thresholds, falsifiability, primary- source Google guidance; kept our Next.js implementation code)
• 6 new: seo-backlinks, seo-local, seo-ecommerce, seo-sxo, seo-content-drift, seo-topical-clusters; +1 reference dataset skill: seo-google-guidelines
• 2 optional, generic-named integration refs: seo-rank-data, seo-crawl-data
• adapted to our style, no brand names in skill names, MIT attribution footer.
• scripts/seed-seo-skills.mjs: backs up, upserts all 20 via SkillsStore (FTS-safe), rebuilds FTS. Run on the prod container to propagate (MCP being unavailable).

FTS fix (root cause found while importing the skills):

• skills upsert switched from INSERT OR REPLACE to INSERT ... ON CONFLICT(name) DO UPDATE. INSERT OR REPLACE churned skills.rowid on every write, orphaning the FTS5 external-content index (skills_fts) and surfacing as fts5: missing row N from content table 'skills' in skill_route after re-import. Stable rowids also let the upsert preserve autolearning columns for free (no more COALESCE-from-subquery), and preserve status on null (importer) vs default active.
• migration 035: AFTER INSERT/UPDATE(OF indexed cols)/DELETE triggers maintain the FTS via the external-content delete+insert protocol, plus a one-time rebuild that repairs existing orphans on any DB (incl. prod at deploy).
• removed the now-redundant manual FTS write from the code (would double-index).
• +5 regression tests (skills-store-fts): FTS stays queryable across re-upserts, stable rowid, autolearning/status preserved, delete de-indexes.

Tests: storage 19, codegraph 294 — all green.