release: merge develop into main

[mickdarling]

Summary

• release the latest query-language phase from develop into main
• include semantic endpoint mode support alongside the standard CRUDE profile
• include query-language guides and helper schemas for aggregations, computed fields, and relationship queries
• include the fixture-driven conformance runner and reference evidence bundles
• include the cross-domain implementation guide for adapting MCP-AQL beyond the Dollhouse reference profile

Included Work

• spec: add advanced query feature guides #249
• spec: add fixture-driven conformance suite #248
• docs: add cross-domain implementation guide #250
• spec: support grouped endpoint families #251

Testing

• branch-level GitHub checks on this release PR
• local validation already run in the source PRs with npm test and npm run docs:dates:check