Always-on service events log + show failure reasons on screen

So that if the service breaks on a machine where nobody enabled logging first
(e.g. a Win7 tester), we still learn WHY:

- New always-on ServiceStore.AppendServiceEvent -> service-events.log in
  ProgramData, independent of any logging toggle (like the update log).
- Service menu status-query failure now shows the actual reason IN the status
  line (a screen reader reads it) AND records it to the events log, instead of a
  bare 'status unavailable' whose reason only went to the off-by-default app log.
- ServiceAction (install/uninstall/start/stop) records request + outcome to the
  events log.
- ServiceEntry (the elevated child) logs each verb's start, and CATCHES a
  System.ServiceProcess load failure to record its reason before rethrowing (so
  the crash file still gets the full stack) — this is the likely Win7 failure.
- 'View service log' falls back to the events log when no runtime diagnostic log
  exists, so there's always something to view after any service interaction.

Recap of coverage: hard crashes -> crash-*.txt (always, no setup). Graceful
service failures -> now the events log + on-screen reason (no setup). Gate 35/35.

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

src/RemSound.App/MainForm.cs

@@ -2254,8 +2254,12 @@ public sealed class MainForm : Form
             }
             catch (Exception ex)
             {
-                status.Text = "Service: status unavailable";
+                // Show the reason right in the status line (a screen reader reads it), AND record it to the
+                // always-on service events log — so even with app logging off (e.g. a Win7 tester) we learn
+                // WHY the service machinery couldn't load, not just that it didn't.
+                status.Text = $"Service: unavailable — {ex.GetType().Name}: {ex.Message}";
                 logFile.Event($"service menu: status query failed {ex.GetType().Name}: {ex.Message}");
+                ServiceStore.AppendServiceEvent($"menu status query FAILED: {ex.GetType().Name}: {ex.Message}");
             }
         };
         return serviceMenu;
@@ -2268,12 +2272,16 @@ public sealed class MainForm : Form
     /// there's nothing here yet, that's the first thing to turn on.</summary>
     private void OpenServiceLog()
     {
+        // Prefer the service's runtime diagnostic log (only exists if the service actually ran with logging
+        // on); otherwise fall back to the ALWAYS-ON service events log, which records every menu/install/
+        // start/stop and any failure reason — so there's a trail to view even if nobody enabled logging.
         var path = ServiceStore.NewestLogFile();
+        if (path is null && File.Exists(ServiceStore.ServiceEventsLogPath)) path = ServiceStore.ServiceEventsLogPath;
         if (path is null)
         {
             var msg = ServiceStore.LoadLoggingEnabled()
-                ? "No service log yet. The service writes one once it starts with logging on — start (or restart) the service, then check back here."
-                : "No service log yet. Turn on logging first: Service menu → Configure service profile → Logging tab → enable service logging, then start (or restart) the service. The log records what the service does and why it is or isn't sending.";
+                ? "No service log yet. The service writes one once it starts with logging on — start (or restart) the service, then check back here. (The service events log appears here too once you install/start it.)"
+                : "No service log yet. Once you install or start the service, its events (and any failure reason) are recorded here automatically. For the fuller runtime log, also turn on logging: Service menu → Configure service profile → Logging tab.";
             MessageBox.Show(this, msg, AppName, MessageBoxButtons.OK, MessageBoxIcon.Information);
             return;
         }
@@ -2359,8 +2367,11 @@ public sealed class MainForm : Form
             if (MessageBox.Show(this, msg, AppName, MessageBoxButtons.YesNo, MessageBoxIcon.Question) != DialogResult.Yes) return;
         }
         logFile.Event($"service: {label} requested (elevated)");
+        ServiceStore.AppendServiceEvent($"{label} requested (elevated)");
         var rc = ServiceControl.RunElevated(verb);
-        logFile.Event($"service: {label} finished with code {rc} ({(rc == 0 ? "success" : rc == -1 ? "cancelled/declined" : "failed")})");
+        var outcome = rc == 0 ? "success" : rc == -1 ? "cancelled/declined" : "failed";
+        logFile.Event($"service: {label} finished with code {rc} ({outcome})");
+        ServiceStore.AppendServiceEvent($"{label} finished: code {rc} ({outcome})");
         if (rc == 0)
             MessageBox.Show(this, $"Service {label} succeeded.", AppName, MessageBoxButtons.OK, MessageBoxIcon.Information);
         else if (rc == -1)