UI Clarity & Quality-of-Life Enhancements

Here's a little patch that brings quality-of-life tweaks, clearer visual cues and the ability to pick up right where you left off

• Continue from where you left off: Added a “Continue” button to the main menu so you can jump back into your last session.
• Persistent settings in the web build: All menu choices and options are now saved in your browser.
• More scraps per base alien: Increased scrap drop from base aliens from 10 to 15 to ease early progression.
• Slowed time in build mode: Building now triggers a 10× slow-motion effect for a more relaxed placement phase.
• Disabled bots greyed-out: Inactive bots are now visibly greyed out, making active units stand out.
• Row highlighting on hover and placement: Hovering over or placing shooting bots highlights the corresponding lane for better visibility.