fix: keep last good AMSAT live lists on fetch failures; whitelist mirror

- Failed whitelist fetch (raw.githubusercontent.com unreachable on some
  networks) no longer wipes the persisted whitelist or admits every ISS
  module alias: fall back to the persisted whitelist, and only persist
  when a stream was actually fetched.
- Multi-match collapse without any whitelist now keeps the primary entry
  (smallest catnum, ISS ZARYA=25544) instead of every alias (DESTINY etc.).
- Failed FM/Linear page fetch keeps the previous lists instead of
  clearing the filters.
- Amateur whitelist gets a jsDelivr CDN mirror as fallback source.

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/source/Sources.kt

@@ -68,9 +68,14 @@ object Sources {
      *  transponder with its NORAD catnum. Used as the authoritative whitelist
      *  of *amateur* satellites, so the virtual filters never match
      *  non-amateur debris (Ariane 6 R/B), retired weather sats (TIROS), or
-     *  ISS station-module aliases (ISS (DESTINY) etc.). */
-    const val amSatActiveUrl =
-        "https://raw.githubusercontent.com/palewire/amateur-satellite-database/main/data/amsat-active-frequencies.csv"
+     *  ISS station-module aliases (ISS (DESTINY) etc.). Primary source plus
+     *  a jsDelivr CDN mirror: raw.githubusercontent.com is unreachable on
+     *  some networks (e.g. mainland China mobile), and a failed whitelist
+     *  fetch would silently disable the module disambiguation. */
+    val amSatActiveUrls = listOf(
+        "https://raw.githubusercontent.com/palewire/amateur-satellite-database/main/data/amsat-active-frequencies.csv",
+        "https://cdn.jsdelivr.net/gh/palewire/amateur-satellite-database@main/data/amsat-active-frequencies.csv"
+    )
 
     /** Virtual satellite-selection types: transponder/activity filters shown
      *  at the top of the type picker. They resolve to live lists (AMSAT pages