feat(text-tool): implement Photoshop-style on-canvas text editor

- Replaced modal dialog with inline on-canvas text editor
- Text objects stored as editable entities (non-rasterized)
- Live preview with transparent textarea overlay
- Click on existing text to re-edit
- Drag transform handles to move text
- Auto-commit on click outside (via overlay)
- Text selection with visible highlight
- Hidden original text during editing to prevent double vision
- Position alignment fixes for editing existing text
- Keyboard shortcuts: Ctrl+Enter to commit, Escape to cancel

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

types/text.ts

@@ -16,10 +16,34 @@ export interface TextSettings {
   letterSpacing: number;
 }
 
+export interface TextObject {
+  id: string;
+  layerId: string;
+  x: number;
+  y: number;
+  text: string;
+  fontFamily: string;
+  fontSize: number;
+  fontStyle: FontStyle;
+  fontWeight: FontWeight;
+  color: string;
+  align: TextAlign;
+  baseline: TextBaseline;
+  lineHeight: number;
+  letterSpacing: number;
+}
+
 export interface TextStore {
   settings: TextSettings;
-  isDialogOpen: boolean;
-  clickPosition: { x: number; y: number } | null;
+
+  // Text objects (non-rasterized text)
+  textObjects: TextObject[];
+
+  // On-canvas editor state
+  isOnCanvasEditorActive: boolean;
+  editorPosition: { x: number; y: number } | null; // Canvas coordinates
+  editorText: string; // Current text being edited
+  editingTextId: string | null; // ID of text object being edited (null for new text)
 
   // Setters
   setText: (text: string) => void;
@@ -34,7 +58,15 @@ export interface TextStore {
   setLetterSpacing: (letterSpacing: number) => void;
   updateSettings: (settings: Partial<TextSettings>) => void;
 
-  // Dialog control
-  openDialog: (x: number, y: number) => void;
-  closeDialog: () => void;
+  // Text object management
+  addTextObject: (textObject: Omit<TextObject, 'id'>) => void;
+  updateTextObject: (id: string, updates: Partial<TextObject>) => void;
+  deleteTextObject: (id: string) => void;
+  getTextObjectAt: (x: number, y: number, layerId: string) => TextObject | null;
+
+  // On-canvas editor control
+  activateOnCanvasEditor: (canvasX: number, canvasY: number, textId?: string) => void;
+  deactivateOnCanvasEditor: () => void;
+  updateEditorPosition: (canvasX: number, canvasY: number) => void;
+  updateEditorText: (text: string) => void;
 }