feat: implement comprehensive text tool (Phase 11)

Add complete text rendering system with the following features:

**Text Tool Core:**
- TextTool class with click-to-place text functionality
- Text cursor and pointer event handling
- Integration with DrawCommand for undo/redo support

**Text Rendering:**
- Multi-line text support with line height control
- Custom letter spacing
- Text alignment (left/center/right)
- Font families: 13 web-safe fonts + 14 popular Google Fonts
- Dynamic Google Font loading via Web Font Loader API
- Font styles (normal/italic) and weights (100-900)

**Text Dialog UI:**
- Full-featured text editor dialog
- Live preview of text with all formatting
- Font family selection (web-safe + Google Fonts)
- Font size (8-500px), style, and weight controls
- Color picker with hex input
- Text alignment options
- Line height slider (0.5-3x)
- Letter spacing slider (-10 to 50px)
- Multi-line text input with textarea

**State Management:**
- text-store with Zustand + persist middleware
- All text settings preserved across sessions
- Dialog state management (open/close)
- Click position tracking

**Integration:**
- Added text tool to tool palette with Type icon
- Registered TextTool in canvas tool system
- Added TextDialog to editor layout
- Full type safety with TypeScript interfaces

**Undoable:**
- Text rendering fully integrated with command pattern
- Each text insertion creates single undo point
- Proper before/after state capture

This completes Phase 11 of the implementation plan, marking
the transition from MVP to a fully-featured image editor.

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

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

components/canvas/canvas-with-tools.tsx

@@ -20,6 +20,7 @@ import {
   MoveTool,
   FreeTransformTool,
   ShapeTool,
+  TextTool,
   type BaseTool,
 } from '@/tools';
 import type { PointerState } from '@/types';
@@ -40,6 +41,7 @@ const tools: Record<string, BaseTool> = {
   move: new MoveTool(),
   transform: new FreeTransformTool(),
   shape: new ShapeTool(),
+  text: new TextTool(),
 };
 
 export function CanvasWithTools() {