Remove dead code found by Periphery on all platforms

Delete declarations that Periphery reports unused on every platform that
compiles them (iOS, macOS, tvOS), including nine views used only by their
own previews. Platform-gated code still used on another platform, device-
only MPV render paths, migration models, CloudKit record names, App
Intents metadata and unused parameters are kept.

Yattee/Services/MediaSources/SMBClient.swift

@@ -343,29 +343,12 @@ actor SMBClient {
 
     // MARK: - Helper Methods
 
-    /// Validates SMB URL format.
-    private func validateSMBURL(_ url: URL) throws {
-        guard url.scheme?.lowercased() == "smb" else {
-            throw MediaSourceError.unknown("URL must use smb:// scheme")
-        }
-
-        guard url.host != nil else {
-            throw MediaSourceError.unknown("SMB URL missing host")
-        }
-    }
-    
     /// Clears cached SMB context for a specific source.
     /// Call this when source credentials change or connection fails.
     func clearCache(for source: MediaSource) {
         contextCache.removeValue(forKey: source.id)
         LoggingService.shared.logMediaSourcesDebug("Cleared SMB context cache for source: \(source.id)")
     }
-
-    /// Clears all cached SMB contexts.
-    func clearAllCaches() {
-        contextCache.removeAll()
-        LoggingService.shared.logMediaSourcesDebug("Cleared all SMB context caches")
-    }
 }
 
 // MARK: - File Download