vc=60: storage usage readouts in cache settings

Each store + Coil image cache shows its actual on-disk byte count
next to its cap chip-row. Closes the loop on vc=59's cache controls
— users can see what each cap is doing instead of guessing.

- StorageUsage.sharedPrefBytes — reads dataDir/shared_prefs/X.xml
  length directly. Cheap, advisory; not authoritative on
  Android's internal SP layout but close enough to be useful.
- StorageUsage.coilDiskCacheBytes — pulls
  SingletonImageLoader.get().diskCache?.size, returns 0 if Coil
  hasn't lazily initialized yet.
- StorageUsage.format — KB/MB/GB renderer with 0 -> '—'.

Usage snapshot is captured once per Settings entry via remember{}
so File.length() doesn't refire on every recomposition.

buildSrc/src/main/kotlin/ProjectConfig.kt

@@ -55,6 +55,6 @@ const val NEWPIPE_APPLICATION_ID_NEW = "net.newpipe.app"
 // vc=19 / 0.1.0-AE — rust pipeline cutover. Extraction via
 // strawcore-core (Sulkta-Coop/strawcore) via the UniFFI wrapper; no
 // NewPipeExtractor in the runtime path.
-const val STRAW_VERSION_CODE = 59
-const val STRAW_VERSION_NAME = "0.1.0-BS"
+const val STRAW_VERSION_CODE = 60
+const val STRAW_VERSION_NAME = "0.1.0-BT"
 const val STRAW_APPLICATION_ID = "com.sulkta.straw"