fix: structural overhaul

[achingbrain]

Refactors routing code to greatly simplify architecture.

1. Document the loading process
2. Display server error/fetch error/origin isolation warning inline
3. Encode query parameters in redirect param
4. Make styling consistent across all pages
5. Add load/about/settings navigation above the fold to reduce on-screen clutter
6. Fix input form error so the 'load content' button shows
7. Allow hard refresh with query params
8. Pre-fill download input with CID/path from current page if available
9. Remove "first-hit" scaffolding as it covers up a query string parsing bug
10. Remove unused code and components
11. Add waitUntil to page.goto in playwright tests to fix race conditions where we expect a 200 status but it can still be redirecting
12. Disable Firefox bounce tracking protection during tests as it deletes the service worker when triggered

Change checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation if necessary (this includes comments as well)
• I have added tests that prove my fix is effective or that my feature works