[Feature] Cross-device sync for tabs / tab groups (opt-in, self-hosted or E2EE)

[kimnamwook1]

Problem to solve

ego (lite) works well as a daily browser, but there is no way to keep saved tab groups / open tabs in sync between two Macs (e.g. desktop + laptop). Chrome's Google-account sync is not available to Chromium forks, and the current "sync" in ego is a one-way import from a local Chrome profile, so it does not help across devices. Extension-based workarounds (Floccus tab sync) are unstable with tab groups.

For users who want ego as their primary browser on more than one machine, this is currently the main blocker.

Proposed solution

Opt-in sync of saved tab groups, pinned tabs, and (optionally) open tabs across devices, without a mandatory cloud account:

• Backend choice: user-provided WebDAV / S3-compatible endpoint, or a self-hosted relay — consistent with the "your data stays yours" principle.
• End-to-end encrypted with a user passphrase if a hosted relay is ever offered.
• Scope control: sync only the user's Spaces; Agent task Spaces excluded by default.

Alternatives considered

• Chrome Sync: unavailable to non-Google Chromium builds.
• Floccus / xBrowserSync extensions: bookmark sync works, tab-group sync duplicates tabs after crash/restore, and they cannot distinguish Agent Space tabs.
• Keeping Chrome as primary and importing into ego: one-way only; groups created in ego never leave the machine.

Additional context

macOS, two devices, ego (lite) as default browser on both. Happy to test a preview build.