feat(seo-schema-generator): merge site-extraction + source-to-schema into one skill

Unify the two schema-generation scenarios into a single slot-17 skill, both
feeding one claims register -> build -> validate(16) pipeline:

- Mode 1 (existing site): NEW scripts/extract_site_claims.py turns URLs / local
  HTML / a directory into a claims register. Existing JSON-LD -> CONFIRMED;
  title/OpenGraph -> PENDING (never auto-shipped). + site-extraction-methodology.md
  and bundled fixtures/site/ demo pages.
- Mode 2 (not-yet-published site): land the source-to-schema engine
  (build_schema_drafts.py, type_templates.json, claims/source registers, 3 refs,
  sample_claims.csv) from the Desktop builder.
- Rewrite SKILL.md (v2.0) around the two-mode framing; the claims register is the
  shared pivot. Only CONFIRMED, non-conflicting claims become schema; unfilled
  template slots are pruned, never emitted as placeholders.
- Retire the old template-fill generator (code/ + desktop/); update root CLAUDE.md.

Self-tested both chains end-to-end: Mode 2 sample -> build -> validate PASS (P0=0);
Mode 1 fixtures -> extract -> build -> validate PASS (P0=0), JSON-LD round-trips with
nested address intact. Fixed two adapter bugs (nested node promotion; relative-path URI).

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

custom-skills/17-seo-schema-generator/desktop/skill.yaml

@@ -1,12 +0,0 @@
-# Skill metadata (extracted from SKILL.md frontmatter)
-
-name: seo-schema-generator
-description: |
-  Schema markup generator for JSON-LD structured data. Triggers: generate schema, create JSON-LD, add structured data, schema markup.
-
-# Optional fields
-allowed-tools:
-  - mcp__firecrawl__*
-  - mcp__perplexity__*
-
-# triggers: []  # TODO: Extract from description