Prepare Glaze 0.7.0 release automation

[turinglambdaai]

Summary

• declare the SemVer release as 0.7.0 while preserving Racket package version 0.7
• add an annotated-tag release workflow with provenance, test, docs, exact-archive smoke, checksum, and GitHub Release gates
• document the release procedure

Validation

• raco test --package glaze (220 tests passed)
• exact generated source ZIP installed into a fresh PLTUSERHOME
• require glaze, glaze/server, and glaze/events succeeded
• raco glaze help succeeded
• workflow YAML parsed successfully