Fix: passkey sound now layers in on password fields

RemSound's password boxes are deliberately NOT PasswordChar-masked (a screen-reader user can't see
a mask), so the key-click hook's "is this a password field?" check (UseSystemPasswordChar /
PasswordChar) was always false and the distinct passkey.wav never played. Password fields now mark
themselves with Tag = KeyClickService.PasswordFieldTag, and the hook checks that (keeping the
masking-flag check as a fallback). Tagged both password fields - ProfilePasswordDialog (which all
password entry routes through, including the send/receive streaming gate) and
ProfilePasswordManagerDialog. So a key click + passkey now layer together on every password keystroke.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/RemSound.App/ProfilePasswordManagerDialog.cs

@@ -60,7 +60,7 @@ internal static class ProfilePasswordManagerDialog
             catch { current = ""; }
 
             var label = new Label { Text = title, AutoSize = true, Anchor = AnchorStyles.Left, Padding = new Padding(0, 6, 10, 6) };
-            var box = new TextBox { Text = current, Anchor = AnchorStyles.Left | AnchorStyles.Right, AccessibleName = $"Password for profile {title}" };
+            var box = new TextBox { Text = current, Anchor = AnchorStyles.Left | AnchorStyles.Right, AccessibleName = $"Password for profile {title}", Tag = KeyClickService.PasswordFieldTag };
             grid.Controls.Add(label);
             grid.Controls.Add(box);
             rows.Add((title, current, box));