chore: bump version to v2026.4.324 and update changelog}
- Bump package.json version from 2026.4.323 to 2026.4.324
- Add v2026.4.323 changelog entry with auto theme mode,
blame view syntax highlighting, footer and submodule fixes,
and publish script simplification
- Update build version references from v2026.4.322 to v2026.4.323
across README.md, INSTALL.md, change-break.md, change-log.md,
todo.md, and artifacts docs