feat: lay the site out as a reading funnel

Five tabs from Start here to Contribute, a level on every page, a device picker on Get your files that lists every registered platform, and platform pages that open on where the files go, the command, the pack and how to check. FAQ and troubleshooting keep the questions asked before installing, the technical ones move to their own page, and getting started points to the pages that took its content.

scripts/generate_readme.py

@@ -659,7 +659,7 @@ def generate_readme(db: dict, platforms_dir: str) -> str:
             "Hashes document what emulator code loads and accepts, not dump"
             " provenance. That boundary, and how it relates to preservation"
             " catalogs such as No-Intro, is drawn in the"
-            f" [FAQ]({SITE_URL}wiki/faq/"
+            f" [technical questions]({SITE_URL}wiki/technical-faq/"
             "#are-these-files-verified-against-original-hardware-dumps).",
             "",
             "1. **Read emulator source code**: trace every file the code loads, its expected hash and size",