float: defer size calculation if initially on dummy output

[mahkoh]

Fixes #1145

[Copilot]

Pull request overview

This PR addresses issue #1145 where floating windows can end up with a 0x0 geometry (invisible) after being moved into an overlay workspace, by deferring/redoing initial float positioning when the workspace/output state transitions away from a dummy output.

Changes:

• Track whether a workspace has been on a dummy output and, on the next real extents update, reposition floats that still need an initial size/position.
• Move initial float position computation into FloatNode::new, including a dummy-output fallback and a shared calculate_float_position helper.
• Add a FloatNode::set_position helper and update call sites/tests to use it.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/tree/workspace.rs	Tracks “was on dummy output” and triggers float repositioning when transitioning to a real output.
src/tree/float.rs	Defers initial float sizing/positioning when created on a dummy output; adds set_position; introduces calculate_float_position.
src/state.rs	Updates float creation to pass inner dimensions/abs position into FloatNode::new (position computed inside FloatNode).
src/it/tests/t0033_float_size_memoization.rs	Updates test to use set_position (but currently contains a coordinate bug needing correction).
src/it/tests/t0028_top_level_restacking.rs	Updates test to use set_position.

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