docs: Android comments say what the app does, not how it came to be (#6277)

Every flagged comment block in the Android app, its tests and its XML/TOML
config, rewritten with the cited issue in view: the constraint is kept, the
story behind it dropped, and issue, milestone, rule, phase and drift ids,
dates and operator quotes removed. "Mirrors the Flutter client's X"
pointers are gone; that client is no longer in the repo.

Comments that no longer matched the code, corrected:
- SyncController: a 410 resets the cursor and re-pulls; it never dropped
  the three local caches.
- PlayerFactory, PlayerModule, AudioCacheIndexEntity, CacheConfig,
  CacheSource: there is no eviction worker and no liked-track bucket;
  SimpleCache evicts by plain LRU over the rolling cap, and the liked cap
  is stored but unenforced.
- CacheSettings, StorageCard: the prefetcher exists (AudioPrefetcher);
  pin-on-like still does not.
- LibraryApi, LibraryRepository, BrowseViewModel: the cache now carries
  the missing-file mark; the browse indexes stay server-backed for one
  source of grouping.
- OutputRoute: UPnP routes exist; only CAST and SONOS are reserved.
- PlayerFactory, RemotePlayerState, OutputPickerController: a failed
  transport command does not drop the UPnP route.
- LibraryScreen: History, Liked and Hidden are real tabs, not placeholders.
- AVTransportClient: the extend loop lives in SonosQueueLoader.
- "the operator" meaning the listener now says "the user".

Verified with a Kotlin lexer comparing every file's non-comment tokens
against HEAD: 394 files, 0 differences.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

android/app/build.gradle.kts

@@ -1,9 +1,9 @@
 plugins {
     alias(libs.plugins.android.application)
     // kotlin-android NOT applied: AGP 9 enables built-in Kotlin by default,
-    // and KSP 2.3.x supports it (PR #2674, merged Oct 2025). serialization
-    // + compose-compiler are language-level Kotlin compiler plugins and
-    // still need explicit application.
+    // and KSP 2.3.x supports it. serialization + compose-compiler are
+    // language-level Kotlin compiler plugins and still need explicit
+    // application.
     alias(libs.plugins.kotlin.serialization)
     alias(libs.plugins.compose.compiler)
     alias(libs.plugins.ksp)
@@ -31,14 +31,9 @@ android {
         //
         // versionCode is minutes since 2020-01-01 at BUILD time. It is the
         // value the platform decides installs by, so it must be monotonic by
-        // construction.
-        //
-        // This comment used to say versionCode was a commit count and that it
-        // was "monotonic forever". It was neither — a commit count runs ahead
-        // on `dev`, so a dev build outranked the `main` release meant to
-        // replace it and Android refused the install as a downgrade. Worth
-        // knowing the claim was here, stated as a reassurance, while the bug
-        // it denied was live.
+        // construction. Not a commit count: that runs ahead on `dev`, so a dev
+        // build would outrank the `main` release meant to replace it and
+        // Android would refuse the install as a downgrade.
         val versionNameOverride =
             (project.findProperty("MINSTREL_VERSION_NAME") as String?)?.takeIf { it.isNotBlank() }
         val versionCodeOverride =
@@ -73,9 +68,9 @@ android {
                 "proguard-rules.pro",
             )
             // Signed with the release key or not at all. Falling back to the
-            // debug key made a missing secret into a published APK that no
-            // install could ever update (family idea #5103, practice 2). An
-            // unsigned build installs nowhere, so the gap shows at once.
+            // debug key would turn a missing secret into a published APK that no
+            // install could ever update. An unsigned build installs nowhere, so
+            // the gap shows at once.
             signingConfig =
                 if (System.getenv("ANDROID_KEYSTORE_PATH").isNullOrEmpty()) {
                     null