Pharos 0.7.0

Persistent cross-platform Mesh. The broker and wire protocol now live in a
portable PharosMeshCore, with a standalone pharos-mesh executable for Linux
servers. Messages receive stable IDs, replies retain a safe preview of their
target, and image/PDF attachments use checksum-verified binary transfer with a
25 MiB limit and atomic storage.

Native group-chat interaction. macOS and iPhone chat views add quoted reply
cards, attachment pickers, previews and downloads, plus a more compact
Slack/Discord-inspired room and message layout. Legacy transcripts remain
readable without migration.

Always-on personal Broker. macOS can target an explicit headless Tailscale
endpoint instead of electing one of the paired Macs as Hub. The Linux service is
hardened with systemd, persists transcripts and files under
/var/lib/pharos-mesh, and needs none of the AppKit/project-launching CLI.

Linux Release and APT automation. GitHub Releases build signed amd64 and
arm64 Debian packages, publish checksums, and deploy a signed APT repository
through GitHub Pages so Ubuntu/Debian users can install and upgrade with apt.