Add first-pass wrangle registry and documentation pipeline

[ebhills]

Summary

• Defines the first Registry contract, schemas, common controls, fixtures, and validation workflow.
• Adds 98 normalized wrangle entries using the agreed source precedence: WranglesPY code, embedded schema metadata, then existing Wrangles-Docs Markdown.
• Pins provenance to WranglesPY revision 7916bf158e8b7e561270a1bea7b808f88956edc4 and adds runtime reconciliation reports.
• Generates 309 machine-readable contracts, raw artifacts, Registry documentation pages, and navigation entries.
• Renames the Docusaurus site directory from my-docs-site to wrangles-docs.

Behavior and compatibility

• Adds a parallel Registry pilot at /wrangles with a visible Registry Pilot navigation item.
• Keeps the existing /wrangle documentation pages and routes intact; this PR does not cut over or replace them.
• Allows missing UUIDs during the pilot so database-assigned identities can be added later.
• Accommodates runtime wrangles without existing quasi-registry Markdown by deriving their initial entries from code and embedded schema metadata.

Validation

• npm run check:registry — passed; all 309 generated artifacts are current.
• npm run build — passed; Docusaurus reported only the previously identified broken-link and broken-anchor warnings outside the Registry work.
• git diff --cached --check — clean before commit.
• Remote branch is one commit ahead of and zero commits behind main.

Follow-up work

A separate presentation-layer round will bring the generated pages to roughly 80% replacement readiness by reusing the existing wrangle styles, improving example presentation, removing internal pilot terminology from the public template, and preserving the richer _sources guidance. The existing pages will remain available until a later reviewed route cutover.

Additional incremental work includes database UUID assignment, expanding fixture-backed examples, content polish, and final redirect/link validation.

Rollback

Revert this PR to remove the Registry pilot and restore the previous site-directory layout. No existing /wrangle documentation pages are removed by this change.