Multi-variable swaps in a single LipSync video

Allow multiple word/phrase swaps within a single LipSync video render, so one personalised video can replace more than one variable from the sheet in the same clip (for example a contact's name and a second dynamic detail).

Current state: LipSync video supports a single swap per render. Multiple swaps in one LipSync video are not yet supported.

Use case: Automated 1:1 outreach videos that personalise two values at once in the same video.

Target: mid-July 2026.