fix(search): cleanup review findings — dead code, FQN refs, naming

- Remove unused `key` param from ExpandableSection
- Replace FQN references with imports in AdvancedSearchPanel and SearchScreen
- Use MetadataEvent.KIND instead of magic `0`
- Remove dead `relayStatuses` collection (only `connectedRelays` used)
- Remove CachedUserResult sealed variant (never constructed)
- Rename SearchHint `identifier` param to `example`

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/search/SearchResult.kt

@@ -20,8 +20,6 @@
  */
 package com.vitorpamplona.amethyst.commons.search
 
-import com.vitorpamplona.amethyst.commons.model.User
-
 /**
  * Represents a parsed search result from Bech32/hex input.
  * Shared between Android and Desktop for consistent search behavior.
@@ -35,13 +33,6 @@ sealed class SearchResult {
         val displayId: String,
     ) : SearchResult()
 
-    /**
-     * User from local cache with full metadata.
-     */
-    data class CachedUserResult(
-        val user: User,
-    ) : SearchResult()
-
     /**
      * Note lookup from note1 or nevent.
      */