Service: config dialog + Service menu

Local checkpoint - NOT for public release.

- ServiceProfileDialog: modal 3-tab editor (Audio send / Audio profile / Connectivity)
  reusing the house controls, with a Save and Close / Cancel / Additional options
  button row. Send-only: send-mode chooser + WASAPI outputs/apps + inputs (no "Send
  my audio" toggle, no receive, no ASIO); codec/rate/lock-to-clock; peers add/remove +
  a Set password button. Additional options sub-dialog = play connect/disconnect sound
  + enable service logging. Edits a Profile clone; returns it on OK.
- Service menu in MainForm: status line + Configure / Install / Uninstall / Start / Stop,
  items enabled per live state on drop-down. Install/uninstall confirm then elevate.
  Configure saves the reserved service profile, points AppConfig at it, stores the
  machine-wide logging choice, and restarts a running service to pick up edits.
- ProfileStore.ReservedServiceProfileTitle ("RemSound service"): the service profile
  lives with normal profiles (so the service Loads it) but ListProfileTitles hides it
  from every picker. ServiceControl reuses that single constant.
- Self-test: the service dialog is now in the accessibility audit (constructs cleanly,
  unique mnemonics, all controls named). Gate 20/20.

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

src/RemSound.App/SelfTest.cs

@@ -795,6 +795,7 @@ internal static class SelfTest
                 () => false, _ => { }, () => { }, () => 0, () => { }, () => { }, _ => { },
                 () => (default(RouterMappingStatus), (IPEndPoint?)null, ""),
                 _ => { }, _ => { })),
+            ("Service profile", () => new ServiceProfileDialog(RemSound.Core.Profile.NewBlank(), false)),
         };
 
         var audited = new List<string>();