v0.1.0-alpha.93

chore: bump alpha.93 + rename macOS updater bundle per arch

release.yml now renames qcode.app.tar.gz → qcode_<target>.app.tar.gz
post-build so the arm64 + x86_64 matrix runs don't collide on upload.
Without this, only one arch's updater bundle survives in the GH
Release and the edge manifest's updater field stays empty for one
or both Mac variants.

This is the first build that publishes a fully-populated updater
manifest. From here, every alpha.92+ install will see new versions
on launch and prompt to auto-update.

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