[mameen]

Summary

• Inserting a date or time into the page did not record an undo step, so Ctrl+Z could not take it back.
• The step is now recorded before the insert.

Tests

• New test undo_takes_back_an_inserted_date in crates/ui-egui/tests/ui.rs, written first and seen to fail.

Checks

• cargo xtask ci: all checks passed, on the branch rebased onto origin/main (d0cc38d).

🤖 Generated with Claude Code

[DWAA1660]

Audit finding: Undo works in the new test, but Redo cannot restore the inserted date. Reproduced on this PR's exact head 99b994ca389809c8988889ec0ddbc7b14e3f4906 in a separate clone by extending its existing real UI test, without changing production code:

// Save this immediately after the existing "the date was inserted" assertion:
let inserted = h.state().body().unwrap_or_default().to_string();
// Keep the existing Ctrl+Z and "undo takes the inserted date back" assertion, then:
ask(&mut h, "ui.key", json!({"key": "Y", "ctrl": true})).expect("redo");
settle(&mut h);
assert_eq!(h.state().body().unwrap_or_default().to_string(), inserted,
           "redo restores the inserted date");

cargo test -p notecraft-ui-egui --test ui undo_takes_back_an_inserted_date -- --exact --nocapture fails at the added Redo assertion:

left:  "plain text"
right: "plain textThursday, 12 November 2026\n"

Repeated with a normal newline-terminated plain text\n fixture: same failure; Undo's assertion passes, Redo's fails. The new remember_step is before the insertion, so the inserted value is not recorded for Redo. Please record the resulting edit as well and cover the full Undo/Redo round trip. Holding this PR out of the merge batch until that history behavior is fixed.