feat(start): show paying Patreon supporters on the Start page

Add a right-hand rail on the Start page listing active paying patrons
(name + pledge amount, highest first) with a "Support on Patreon" button.
The list is fetched once at boot from the Patreon API in the background;
free followers, $0 tiers, declined and former patrons are excluded.

The creator access token is read at build time from OCS_PATREON_TOKEN
(option_env!), so it never lives in source or git — the release workflow
passes it from a repo secret, and build.rs re-bakes when it changes.
Without a token the rail just shows the support button.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/lib.rs

@@ -7,6 +7,7 @@ pub mod command;
 pub mod entities;
 pub mod io;
 pub mod modules;
+pub mod patreon;
 pub mod plugin;
 pub mod scene;
 pub mod snap;