Fix IME composition handling in option inputs

[don9x2E]

Summary

This PR now includes a follow-up fix after the initial IME handling patch.

• Prevent unintended option creation while IME composition is in progress
• Move new option creation for the local "Add a new answer option" row to explicit user intent
  • create only on Enter (after composition ends) or explicit + button click
• Keep normal live updates for already-created options
• Move focus to the next empty local option after creating one with Enter
• Fix delayed "Delete form" confirmation dialog opening by rendering the dialog outside the actions slot

Why this follow-up was needed

The previous attempt improved composition guards, but real Korean IME usage still hit edge cases where input-driven side effects could trigger unexpectedly in the local option row.

In practice, automatic creation on input was still risky under composition timing differences across browsers/IME implementations.

Behavioral change and trade-off

The local empty option row no longer auto-creates an option purely from input events.
Instead, creation is explicit (Enter or + button).

This slightly reduces automation, but removes IME race/side-effect paths and gives deterministic behavior for CJK input users.

Repro (before)

• Create form
• Add multiple-choice/dropdown/radio options
• Type Korean with IME in the local "Add a new answer option" field
• Observe unexpected creation timing / side effects in some flows

Verification (after)

• During IME composition: no automatic option creation
• After composition ends: Enter creates exactly one option
• + button creates exactly one option
• Focus moves to the newly appended empty local option row
• "Delete form" shows confirmation dialog immediately on click

[Chartman123]

@don9x2E thanks for your fix :) please sign-off your commit

[Chartman123]

Looks good from my point of view

[Chartman123]

/backport to stable5.2

[don9x2E]

Follow-up update pushed in commit 4b8ae6d.

What was added after the approved IME patch:

• local option row now creates options only on explicit intent (Enter after composition end or + button)
• focus moves to the next empty local option after creating one
• delete-form confirmation dialog now opens immediately (moved out of actions slot)

This resolves the remaining Korean IME edge-case observed in real usage.

[don9x2E]

Design proposal only (no code change): restoring auto-create safely

If we want to bring back auto-create for the local option row later, a safer staged approach is:

1. Keep current explicit mode as default.
2. Re-enable auto-create only for non-IME input paths first.
3. Add a strict guard layer for IME paths:
   • never create on input/composition events
   • allow create only after compositionend + explicit user intent (Enter/click)
4. Add browser/IME matrix tests (Korean/Japanese/Chinese IME, Chromium/Firefox/WebKit).
5. Optional feature flag (or config) to compare behavior before making it default.

Acceptance criteria for any auto-create restoration:

• zero unintended creates during composition
• exactly one create per explicit intent
• stable focus behavior after creation
• no regressions for existing option update flow.