v1.0.4 — Antigravity sync restored, multi-monitor fixes, perpetual licences

Upgrading from 1.0.2, so this also covers 1.0.3.

• Antigravity: Sync and Replay work again after Antigravity's update split it into two apps and moved its data. Both are now read from transcript.jsonl on disk, across ~/.gemini/antigravity and ~/.gemini/antigravity-ide. Opening a folder in Antigravity works again as well.
• Multi-monitor: dragging between displays with different scaling no longer snaps the window back to the corner; maximise/restore behaves on mixed-DPI setups, and restore now yields a comfortable size instead of a near full-screen clone. Embedded IDEs rescale when the host crosses a DPI boundary.
• VS Code (Copilot): user prompts are recovered from Copilot's chat session store, fixing handoff blocks that showed "(assistant initiative)" with no prompt on Copilot 0.57 / VS Code 1.129.
• Licensing: support for the pay-once Basic / Personal / Team tiers. Usage never expires; the one-year update entitlement is tracked separately and the status chip reports it correctly. A new key can be entered in-app when a licence has expired.
• Replay storage moved to ~/.agenthub/replay/{workspace-hash} with cascade delete, backup retention and turn-log compaction; new snapshot blobs are Brotli compressed and existing ones still read.
• Sync: handoff toast, clickable warning pill, Sync Activity window, global MCP server registration, smaller workspace footprint.
• Internal anti-tamper hardening with no behaviour change for licensed users.

In-place upgrade preserves the licence cache and the trial timer; caches written by older versions keep working and nobody has to re-activate.