OC Random Block Placement

# Random Block Placement v0.3.0

## ✨ Completely redesigned menu
- New three-column layout: your **Selection** on the left, your inventory in the middle, your **Presets** on the right.
- The menu now adapts to your window size and GUI scale. On small screens, Selection and Presets become tabs.
- Clear text buttons with tooltips replace the old icon buttons.
- Hover a slot to see the block's name and its chance.
- New **Placement: ON/OFF** button directly in the menu.
- Press **B** again to close the menu.

## 🎲 Percentages instead of weights
- Set each block's chance directly in **%** (Shift+click a block, or click its row in the Selection panel).
- The other blocks share the rest and keep their proportions: setting Stone to 50% out of three blocks at 33% gives 25% to each of the others.
- Newly added blocks get an equal share.

## 📚 Better presets
- Select a preset, then **Load**, **Overwrite with selection** or **Delete** it. Destructive actions ask for confirmation.
- Double-click a preset to load it. Hover it to preview its blocks.
- Shows which preset is loaded, and marks it **(modified)** when your selection has changed.
- **Clear selection** no longer looks like it deletes a preset, and can no longer wipe one by accident.

## ⚙️ New settings menu
Open it with the ⚙ button:
- **Save changes**: automatically when closing the menu (default), or manually with Apply/Cancel.
- **Missing blocks**: when a selected block runs out, keep placing with the others (default), do the same without a warning, or turn placement off.
- **HUD position**: top center, top left, top right, above the hotbar, or hidden.

## 🖥️ Improved HUD
- Shows "Random placement" and the name of the loaded preset (with "(modified)" when it differs).

## 🐛 Fixes
- Resizing the window no longer discards unsaved changes in the menu.
- Closing the menu with Esc no longer loses your changes (in the default save mode).
- Running out of one block no longer turns placement off for the whole selection (it can still be configured to).

> Existing configs and presets are kept.