fix: prevent IME double-resync from stripping list bullet after Enter

[tfkci]

Problem

When the user presses Enter at the end of a list item, checkForParagraphs creates a new paragraph and inserts its startText (e.g. "• " or "1. ") programmatically into tempTextFieldValue. Some IMEs — in particular Samsung Keyboard on Galaxy devices — respond to this insertion by sending one or more removal callbacks that remove exactly those startText characters from the new, still-empty paragraph.

These callbacks go through TextFieldKeyInput (dispatchKeyEvent) rather than the standard IME composition protocol, so they arrive as normal onValueChange calls. Without a guard, each one is treated as a user Backspace, demoting the paragraph type to DefaultParagraph and losing the bullet/number formatting.

The issue is especially visible with Samsung's word-prediction keyboard, which tends to send the resync twice (double-resync). A single-shot boolean guard (armed once, cleared on first resync) would leave the second resync unprotected.

Fix

justInsertedListParagraph flag — armed by checkForParagraphs immediately after it inserts a non-empty startText for a new list paragraph.

isComposeResync positional check in handleRemovingCharacters — fires when ALL of the following are true:

• justInsertedListParagraph is set
• the paragraph is a list type
• the paragraph body is empty (only startText exists, nothing typed yet)
• the removal count equals exactly the startText length
• the removal starts exactly at the startText position

On resync detection: restore the startText into tempTextFieldValue (so updateAnnotatedString sees no net change) and do NOT clear the flag — every subsequent identical resync is handled the same way. The flag is cleared on the first real user action (non-resync removal, or next character typed).

Tests

Three new regression tests in RichTextStateIMETest:

• testSingleResyncAfterEnter_unorderedList
• testDoubleResyncAfterEnter_unorderedList
• testDoubleResyncAfterEnter_orderedList

All existing tests continue to pass.

Affected devices

Samsung Galaxy A-series, M-series, and other Samsung devices with Samsung Keyboard word suggestions enabled. Potentially any IME that routes certain operations through dispatchKeyEvent.