Persist and re-apply a chosen skin tone in the grid, recents and search

[Fintasys]

Closes #262

Summary

Adds optional support for remembering a user's skin tone choice and re-applying it for display and selection in the grid, recents and search — controlled entirely through SkinToneConfig. Previously SkinToneConfig only controlled visuals and there was no way to make the grid or recents show a previously selected tone.

What changed

New SkinToneConfig settings

property	description	default
defaultSkinTone	Global skin tone applied to every skin-tone-capable emoji in the grid/recents/search	null (base glyph, previous behavior)
skinToneResolver	Per-emoji callback String? Function(Emoji) returning the tone to display; falls back to defaultSkinTone when it returns null	null

A resolveSkinTone(Emoji) helper resolves the effective tone (resolver takes precedence, then the global default).

SkinToneConfig(
  defaultSkinTone: SkinTone.medium,
  skinToneResolver: (emoji) => myPreferences[emoji.name], // optional per-emoji lookup
)

Display + selection

• EmojiPickerUtils.applyDisplaySkinTone(emoji, skinToneConfig) returns the toned glyph for display/selection when a tone applies, otherwise the emoji unchanged. hasSkinTone is preserved so the indicator and long-press picker keep working on those cells.
• The default grid and the search view now apply this for both the rendered cell and the LayerLink key, so tapping a toned cell selects the toned glyph. Recents display the tone too, since recent entries keep hasSkinTone.

Correctness fixes (from the issue's note)

• applySkinTone now strips any existing skin tone modifier before applying a new one, so re-toning an already toned glyph no longer produces invalid double-modifier sequences (e.g. 👋🏻🏽).
• The long-press overlay strips the existing tone first, so the "no tone" cell shows the base glyph and re-picking always applies the new tone to the base, not the already-toned glyph.
• Exposed a public EmojiPickerUtils.removeSkinTone.

Backward compatibility

With no defaultSkinTone/skinToneResolver set, applyDisplaySkinTone returns the base glyph and every code path is unchanged — existing behavior and tests are preserved.

Tests

Added unit tests for applySkinTone on already-toned glyphs, removeSkinTone, SkinToneConfig.resolveSkinTone, and applyDisplaySkinTone (default, disabled, non-toneable, precedence).

🤖 Generated with Claude Code

https://claude.ai/code/session_01EP92uNBmLFz6ckKR8MHueg

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