[players] Stop resizes from corrupting text notes in editing

[frankrousseau]

Problem

• A canvas resize while a text note was still in editing (fullscreen exit via the toolbar button, window resize) corrupted the stored annotation: fabric's clear() fires object:modified after setDimensions, so the note was serialized with old-box coordinates against the new dimensions. left/top/scale were multiplied by the resize ratio and the note rendered off-canvas for everyone, while its timeline mark survived.

Solution

• Exit text editing before setDimensions so the final text is saved against matching dimensions.
• Mute onObjectModified during programmatic canvas clears, like onObjectAdded and onErasingEnd already were, with a regression test on the clear path.