Undo/redo does not track list operations and undoes the wrong action

[Wavesonics]

Description

Undo/redo is broken when the most recent action is a list (rich-span) operation.

Example: type a character, then select some lines and turn them into a numbered list.

• Ctrl+Z removes the numbered list and also reverts the character you typed before it.
• Ctrl+Y does not bring the list back — it re-applies the character instead.

So the list toggle is effectively invisible to the history stack, and undo/redo operate on the previous edit.

Expected

Toggling a list should be a single, independently undoable/redoable step.

Root cause

addRichSpan(...) / removeRichSpan(...) mutate richSpanManager directly and never call editManager.recordEdit(...) — see src/commonMain/kotlin/com/darkrockstudios/texteditor/state/TextEditorState.kt:787-810. Because the list toggle isn't pushed onto the undo queue (TextEditHistory, src/commonMain/kotlin/com/darkrockstudios/texteditor/state/TextEditHistory.kt), undo()/redo() pop the prior text edit instead.

Fix likely means recording rich-span add/remove as history entries (a new TextEditOperation variant or metadata) so they round-trip through undo/redo.

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Reported by a user of the Hammer editor.

[Wavesonics]

Scoping update after investigation.

Toggling a list/blockquote/code fence routes toggleOrderedList/toggleBulletList/toggleBlockquote → toggleLineBlock → applyLineBlock/demoteLineBlock, which changes paragraph indent via updateLine and adds a line-anchored rich span — neither recorded in undo history. So undoing a list toggle isn't tracked and Ctrl+Z falls through to the previous edit, exactly as reported.

PR #26 (descoped + retitled) adds undo/redo for standalone rich spans (highlight/link/HR) but intentionally does not cover line-block toggles, since recording only the span would leave the paragraph indent un-undone (a half-applied block).

This issue stays open to track the real fix: record a compound/atomic history entry for line-block toggles capturing both the updateLine text change and the span change, so undo/redo restores both halves.