android: the room list filtered by name, the rest on demand

Soulseek lists hundreds of rooms; the phone showed the first 80 and no way
to the rest. Community → Rooms now has a filter by name and extends the
list 200 at a time.

src/mobile/shell.css

@@ -1365,3 +1365,6 @@ html[data-motion="off"] *, html[data-motion="off"] *::before, html[data-motion="
 /* the lyrics face's way to its tools */
 .lyr-tools { display: block; margin: 18px auto 8px; padding: 7px 14px; border-radius: 999px; background: rgba(255, 255, 255, 0.08); color: var(--text-secondary); font-size: 12.5px; font-weight: 700; }
 .lyr-tools:active { background: rgba(255, 255, 255, 0.14); }
+
+/* Community: the room filter sits with the section, not the page's own field */
+.sfield.roomfilter { margin-top: 2px; }