[snowyukitty]

Fixes #3848.

Offset the stored Molang text rather than its export-normalized form. Keep line breaks around adjusted constants and in multi-line return expressions, and leave zero-offset axes untouched. Export normalization remains in get(). Inversion also preserves operands across CRLF/tab whitespace and handles multi-line returns.

Validation from the repository root:

• npm run build-web
• npm run build-electron
• npm run generate-types

Automated Chromium checks covered position, rotation and scale expressions, LF/CRLF, leading and trailing constants, trailing semicolons, multi-statement returns, pre/post data points, repeated offsets and tiny deltas. A real gizmo drag, undo/redo and an in-memory project codec compile/load round trip retained the edited text. Additional component checks exercised global/local moves, graph dragging, graph actions and the post-value slider. Desktop execution was not tested.

To reproduce, select a position or rotation keyframe and run this in the application console:

const kf = Timeline.selected[0];
kf.set('x', '5 + math.sin(q.anim_time)\n+ math.sin(q.anim_time*50)');
kf.offset('x', 25);
console.assert(kf.data_points[0].x === '30 + math.sin(q.anim_time)\n+ math.sin(q.anim_time*50)');

The same line break should survive dragging the gizmo. The automated project round-trip check uses an in-memory codec compile/load.