Initial commit of grid line function

docs/USER_GUIDE.md

@@ -134,6 +134,40 @@ These tools align selected objects horizontally or vertically on the slide.
    - **Middle** - Centers all shapes vertically
    - **Bottom** - Aligns all shapes to the bottom edge
 
+## Grid & Guidelines Tools
+
+These tools help you align and position elements precisely on slides using grids and guidelines.
+
+### Custom Grid
+
+Creates a customizable grid overlay on the current slide to help with precise positioning and alignment.
+
+**How to use:**
+1. Navigate to the slide where you want to add a grid
+2. In the Grid & Guidelines section, configure the grid options:
+   - **Spacing** - Set the distance between grid lines (in points)
+   - **Opacity** - Adjust how visible the grid appears
+   - **Color** - Choose from blue, red, yellow, or green
+3. Click "Create Grid" to add the grid to the current slide
+4. Click "Remove Grid" to clear the grid from the slide
+
+**Note:** The grid appears only on the current slide and is for visual reference only - it won't appear in presentation mode or exports.
+
+### Guidelines
+
+Add precise horizontal or vertical guidelines at specific positions on your slide.
+
+**How to use:**
+1. Navigate to the slide where you want to add guidelines
+2. In the Grid & Guidelines section:
+   - **Position** - Set the position of the guideline (in points from top/left)
+   - **Type** - Choose horizontal or vertical
+   - **Color** - Select a color for the guideline
+3. Click "Add Guideline" to add the specified guideline
+4. Click "Remove All" to clear all guidelines from the slide
+
+**Tip:** Use different colors for different types of guidelines (e.g., blue for margins, red for key alignment points).
+
 ## Tips and Best Practices
 
 ### Selection Order Matters