feat(settings,ui): custom-source toggles default off; new UI Settings card; bump to 4.4.9

Two changes per user request:

1. Data source toggles default OFF with legacy-URL migration
   (continuation of the 4.4.8 fix, now also in the dialog): old
   example.com placeholder URLs are replaced by the real defaults and
   the custom toggles stay off, so the online update never points at a
   dead source after upgrading.

2. New "UI Settings" card between Other Settings and Credits:
   one switch per bottom-navigation page (卫星/过境/雷达/匹配/漫游/地图/设置
   in fixed order). Turning a page off removes it from the nav bar and
   the remaining items close up automatically; order is never
   rearranged. The Settings entry is always visible (switch disabled)
   so the user can never lose access to settings. Persisted via
   OtherSettings.hiddenScreens (StringSet of Screen.screenId; screenId
   added to the Screen sealed class - simpleName is unsafe under R8).

Version bump per fork convention: 4.4.8 -> 4.4.9, versionCode 449.
What's-new updated in en/zh/tr.

Verified: core:data + core:domain tests pass, all modules compile.

core/data/src/main/java/com/rtbishop/look4sat/core/data/repository/SettingsRepo.kt

@@ -77,6 +77,7 @@ class SettingsRepo(
     private val keyStateOfUtc = "stateOfUtc"
     private val keyStateOfLightTheme = "stateOfLightTheme"
     private val keyStateOfNightMode = "stateOfNightMode"
+    private val keyHiddenScreens = "hiddenScreens"
     private val keyStationAltitude = "stationAltitude"
     private val keyStationLatitude = "stationLatitude"
     private val keyStationLongitude = "stationLongitude"
@@ -357,6 +358,7 @@ class SettingsRepo(
                 putString(keySstvMode, new.sstvMode)
                 putLong(keyLowElevation, new.lowElevation.toRawBits())
                 putLong(keyHighElevation, new.highElevation.toRawBits())
+                putStringSet(keyHiddenScreens, new.hiddenScreens.toSet())
             }
             new
         }
@@ -372,6 +374,7 @@ class SettingsRepo(
         shouldSeeWarning = preferences.getBoolean(keyShouldSeeWarning, true),
         shouldSeeWhatsNew = preferences.getBoolean(keyShouldSeeWhatsNew, true),
         sstvMode = preferences.getString(keySstvMode, null) ?: "Auto",
+        hiddenScreens = preferences.getStringSet(keyHiddenScreens, emptySet())?.toList() ?: emptyList(),
         lowElevation = Double.fromBits(preferences.getLong(keyLowElevation, 15.0.toRawBits())),
         highElevation = Double.fromBits(preferences.getLong(keyHighElevation, 45.0.toRawBits()))
     )