fix: preserve letterSpacing and shadows from selectedTextStyle in text editor input

[faizahmaddae]

Problem

The TextEditorInput widget hard-codes letterSpacing: 0 and shadows: [] in its style copyWith call (text_editor_input.dart#L206-L212):

style: widget.selectedTextStyle.copyWith(
  color: widget.textColor,
  fontSize: widget.textFontSize,
  letterSpacing: 0,           // ← overrides any user-set value
  decoration: TextDecoration.none,
  shadows: [],                // ← overrides any user-set shadows
),

This means any letterSpacing or shadows set on selectedTextStyle (e.g. via setTextStyle(style.copyWith(letterSpacing: 5))) is silently discarded in the live text input preview.

Observed behavior

Context	letterSpacing respected?	shadows respected?
Hint text (placeholder)	✅ Yes	❌ No (hintStyle also overrides)
Live typing preview	❌ No — always 0	❌ No — always empty
Final rendered layer (LayerWidgetTextItem)	✅ Yes	✅ Yes

The values are correctly stored on the TextLayer and render properly once the text is placed on the canvas, but users cannot see the effect while editing. This makes letter spacing and shadow controls appear broken during the editing experience.

Root cause trace

1. User adjusts letter spacing / shadow → TextEditorState.setTextStyle(style.copyWith(letterSpacing: value)) → selectedTextStyle is updated correctly
2. TextEditorInput receives updated selectedTextStyle as a prop ✅
3. _buildInputField() applies selectedTextStyle.copyWith(letterSpacing: 0, shadows: []) → overrides both values ❌
4. RoundedBackgroundTextField receives style with zeroed-out values → preview shows no spacing or shadows

Fix

Removed the letterSpacing: 0 and shadows: [] lines so the input field respects whatever values are already set on selectedTextStyle. When these properties are not explicitly set, they default to null (Flutter's default behavior), so there is no change in behavior for the default case.

 style: widget.selectedTextStyle.copyWith(
   color: widget.textColor,
   fontSize: widget.textFontSize,
-  letterSpacing: 0,
   decoration: TextDecoration.none,
-  shadows: [],
 ),

Impact

• 2 lines removed, zero new lines added
• No behavior change when letterSpacing / shadows are not explicitly set (defaults to null)
• Enables real-time preview of letter spacing and shadow changes in the text editor input
• Consistent with how the final layer rendering already works (LayerWidgetTextItem preserves both properties)