Lots of small fixes

[mikemaccana]

Thanks for the demo project Silvestre! Here's a bunch of minor fixes, mainly getting rid of warnings and adding some not-so-obvious things to the documentation:

• Use current Vite and SvelteKit
• Use localnet by default in both Anchor and Svelte
• Use the current username (rather than silvestrevivo) for Solana CLI config
• Fix button being off to the side when screen is narrow
• Fix most warnings
  • Fix security warnings in anchor and Svelte app installs
  • Fix Svelte accessibility warnings
  • Fix Svelte language server warning
  • Fix TypeScript deprecation warnings
  • Fix UI using red warning class when wallet is connected
• Make log message less mysterious and fix Svelte sigil so it runs when the value changes
• Docs
  • Add instructions to configure a wallet to use localhost
  • Lots of small English fixes
• Remove Slope, it's now unsupported and hacked
• Use npm consistently (rather than yarn for the Anchor app and npm for the Svelte app)

Fixes #23