Change path handling to make it cross–platform, and fix compilation errors

[slonkazoid]

I had descriptive commits but the local git repo corrupted while I was working somehow ??? so I had to make one giant commit but here's a rough list of what I changed:

• Set up formatter rules (based on existing formatting) & format all code
• Update JS & Rust dependencies
• Fix Svelte component name capitalization to match references in code
• Fix path handling in Rust
• Fix opening directories in the file manager
• Make language referring to paths platform–agnostic
• Add build instructions
• switch to steam:// for launching tf2
  • steam://run/<appid>//<args>/ protocol does not pass launch options to apps ValveSoftware/steam-for-linux#12264
• and various performance optimizations I guess?

[slonkazoid]

fixes #3

[Mark-Prime]

Somehow I missed this PR entirely! Reviewing it! And I'll get the conflicts and stuff resolved for you (those are probably my fault anyway)

This is awesome!

[slonkazoid]

i'll fix the corrupted files and fix conflicts once i'm on desktop. thanks for reviewing !

[slonkazoid]

the postcss config is matching .svelte files

    Finished `dev` profile [unoptimized + debuginfo] target(s) in 2.60s
     Running `target/debug/melies`
9:00:03 PM [vite] Internal server error: [postcss] /home/slonk/repos/Melies/src/routes/+page.svelte?svelte&type=style&lang.css:1:1: Unknown word <script>
  Plugin: vite:css
  File: /home/slonk/repos/Melies/src/routes/+page.svelte?svelte&type=style&lang.css:1:0
  1  |  <script>
     |  ^
  2  |    import EventViewer from "$lib/event_viewer/EventViewer.svelte";
  3  |    import Hero from "$lib/home/hero.svelte";
      at Input.error (/home/slonk/repos/Melies/node_modules/postcss/lib/input.js:135:16)
      at Parser.unknownWord (/home/slonk/repos/Melies/node_modules/postcss/lib/parser.js:595:22)
      at Parser.other (/home/slonk/repos/Melies/node_modules/postcss/lib/parser.js:437:12)
      at Parser.parse (/home/slonk/repos/Melies/node_modules/postcss/lib/parser.js:472:16)
      at parse (/home/slonk/repos/Melies/node_modules/postcss/lib/parse.js:11:12)
      at new LazyResult (/home/slonk/repos/Melies/node_modules/postcss/lib/lazy-result.js:165:16)
      at Processor.process (/home/slonk/repos/Melies/node_modules/postcss/lib/processor.js:53:14)
      at runPostCSS (file:///home/slonk/repos/Melies/node_modules/vite/dist/node/chunks/dep-BHkUv4Z8.js:32399:52)
      at async compilePostCSS (file:///home/slonk/repos/Melies/node_modules/vite/dist/node/chunks/dep-BHkUv4Z8.js:32379:17)
      at async compileCSS (file:///home/slonk/repos/Melies/node_modules/vite/dist/node/chunks/dep-BHkUv4Z8.js:32310:26)