fix: SMB share enumeration, BrowseView polish, sign out, Login branding

- Fix "Bad Network Name": BrowseView at root "/" for SMB now calls
  listShares() instead of listDirectory with empty share name.
  SMBClient.listShares() filters IPC/admin/hidden ($) shares.
- Add listShares() to NASTransferProtocol; implement in SMB (filters
  ipc/special/$-suffix) and SFTP (returns []).
- BrowseView: premium error state (wifi.exclamationmark icon + Retry
  button with ScaleButtonStyle), empty state, safeAreaInset bottom bar
  replacing toolbar bottomBar (shows current path chip + compact Select
  button), proper disabled state for root selection on SMB.
- FolderRow: replace hardcoded .white with AppTheme.inkInverse for dark
  mode correctness; use folder.fill icon; ScaleButtonStyle for tap feedback.
- LoginView: larger logo (80pt), bolder "Kisani" wordmark (32pt bold),
  tagline, staggered spring entrance animations (0.08-0.36s delay).
- SettingsView: Sign Out button in ACCOUNT section with
  confirmationDialog (destructive, clears connection + resets session).
- ConnectionStore: signOut() resets isSessionActive, onboardingPhotoShown,
  and clears savedConnection (triggers Keychain delete).

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

Services/SFTPService.swift

@@ -34,6 +34,8 @@ final class SFTPService: NASTransferProtocol {
         isConnected = false
     }
 
+    func listShares() async throws -> [String] { [] }
+
     func listDirectory(at path: String) async throws -> [NASItem] {
         guard let sftp else { throw BackupError.connectionFailed("Not connected") }
         do {