feat: install the Quest build from the website

A Quest page on the public site (/quest) installs a DorkNet .xapk from
Chrome or Edge over WebUSB, with no adb, SideQuest or scripts: pick the
.xapk, connect the headset, install. It installs the APK, copies the OBB
to its install path (skipped when an identical one is already there) and
launches the app, with progress bars and plain-language errors for an
unsupported browser, a headset held by adb/SideQuest, a disconnect and a
copy signed with a different key.

The .xapk is read from the player's own disk: the APK and OBB are stored
uncompressed, so they stream straight out of the file without loading
1.4 GB into memory, and the server never hosts game files.

Uses Tango (@yume-chan/adb 2.6.4 and friends, MIT), pinned and bundled;
the page is lazy-loaded so the rest of the site doesn't grow. Credited in
NOTICE; README, DorkNet.Quest/README.md, docs/quest.md and the packaged
README.txt point players at the page.

DorkNet.Quest/scripts/package.ps1

@@ -150,7 +150,9 @@ $($manifest.name) $verName - Rec Room for DorkNet (Meta Quest)
 
 1. Turn on developer mode for your headset (Meta Horizon phone app), plug it
    in over USB and accept "Allow USB debugging" inside the headset.
-2. Install:
+2. Install. Easiest: open the Quest page of your DorkNet server's website
+   (https://<server>/quest) in Chrome or Edge, pick this .xapk and follow the
+   steps. Or use the scripts here:
      Windows:        double-click install.cmd
      macOS / Linux:  ./install.sh
    The installer needs adb (Android platform-tools) on PATH or in