[Feature] Image Resizer

### Summary
Resize images by custom pixel dimensions or percentage.

### Files to create/edit
- `src/pages/tools/ImageResize.tsx` → create
- `src/App.tsx` → add import + route `/tools/image-resize`
- `src/pages/Tools.tsx` → add to `allTools[]`

### Implementation notes
- Input: px width/height or % scale
- Aspect ratio lock toggle
- Supports JPG, PNG, WEBP
- Live preview of output dimensions

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