Fix: Multiline Entry ignores scroll position on mobile TouchDown (#6307)

[AmeeteSh-A]

Description:

TouchDown in widget/entry.go was directly reading ev.Position without accounting for the internal scroll offset. This caused the cursor to jump to the wrong line on mobile devices when a multiline entry was scrolled.

This patch mirrors the existing desktop MouseDown logic by adding e.scroll.Offset to the tap coordinates, ensuring the cursor lands exactly where the user taps.

Additionally, I added TestEntry_TouchDown_AccountsForScroll in a new internal widget/entry_touch_test.go file to prevent future regressions.

Fixes #6307

Checklist:

• Tests included.
• Lint and formatter run with no errors.
• Tests all pass.

[andydotxyz]

Excellent catch, thanks so much for the clean fix

[andydotxyz]

Just applying a whitespace fix to try and get this passing CI

[coveralls]

coverage: 59.833% (-0.007%) from 59.84% — AmeeteSh-A:fix-mobile-entry-scroll into fyne-io:develop