fix: resolve compiler warnings across modules

Clears real Kotlin compiler warnings surfaced across quartz, cli,
relayBench, amethyst, and desktopApp:

- quartz Sha256/EventHasher/ScratchLocal: ThreadLocal.get() is nullable
  in Kotlin; assert non-null (withInitial never yields null).
- quartz GitHttpClient: PriorityQueue.poll() under isNotEmpty() is
  non-null; assert it.
- relayBench CorpusDownloader: drop redundant !! on smart-cast Long;
  Jackson fields() -> properties().
- cli GrapeRankCommand: drop redundant ?. where latest is smart-cast.
- PodcastRemoteContent: OkHttp body is non-null; drop dead elvis.
- Dead/redundant expressions: remove no-op when-branch values and a
  redundant trailing Unit (HomeScreen, LocalCache, EmbeddedTabLayer,
  ParticipantHostActionsSheet, NestActionBar, ControlWhenPlayerIsActive,
  ShareNoteAsImageScreen exhaustive-when else).
- CalendarEventDetailScreen / SetPasswordDialog / ProfileClinkOfferResolver:
  drop always-true conditions (reorder to keep smart-casts).
- WalletColumnScreen: OkHttp body non-null; drop unreachable null-guards.
- PcmTapRegistry: the @OptIn used androidx.annotation.OptIn, which does
  not opt into Kotlin's ExperimentalCoroutinesApi; use kotlin.OptIn.
- GitRepositoryScreen: suppress the standard ViewModel-factory cast.
- PushNotificationReceiverService: suppress override-of-deprecated.
- Desktop GlobalScope call sites: @OptIn(DelicateCoroutinesApi::class).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016GMqkg1ndvFihEwZcENiRs

cli/src/main/kotlin/com/vitorpamplona/amethyst/cli/commands/GrapeRankCommand.kt

@@ -568,7 +568,7 @@ object GrapeRankCommand {
                         "provider" to provider,
                         "relay" to relay.url,
                         "changed" to false,
-                        "based_on" to latest?.id,
+                        "based_on" to latest.id,
                     ),
                 )
                 return 0
@@ -744,7 +744,7 @@ object GrapeRankCommand {
             latest?.serviceProviders()?.any {
                 it.service == service && it.pubkey == providerPubkey && it.relayUrl == relay
             } ?: false
-        if (alreadyListed) return latest?.id
+        if (alreadyListed) return latest.id
 
         val tag = ServiceProviderTag(service, providerPubkey, relay)
         val event =