feat(stream): retry a dropped push instead of ending the session (TASK 32·1)

A dead encoder used to run the whole stop path, so a one-second blip ended the broadcast. Now a dropped
push is relaunched against the same ingest while the broadcast is still alive.

- `Services/StreamRetryPolicy.cs` — immediate, +1 s, +2 s, +3 s. Minimum waits on purpose (creator
  ruling): YouTube's grace is short, so every second not pushing is grace spent.
- `Services/StreamRecovery.cs` — the loop, with the audio pipe recreated before every attempt (its
  server is single-instance and unusable after the old client dies, so a naive relaunch fails on a
  missing input). After a push comes up it asks the API whether the broadcast survived: "complete"
  ends recovery as `BroadcastComplete` instead of showing a live sign over a dead stream; an API
  hiccup counts as recovered rather than ending a healthy session.
- `FramePump.EncoderFailed` — a dead push is recoverable; a compositor fault still goes through
  `Failed` and ends the session, because retrying it would loop.
- `MainViewModel.Recovery.cs` — wires the steps, reports each episode into the left panel alert stack
  (one row per episode, updated in place, log range painted), and cancels on Stop.
- Alert stack polish: a rule and a gap now separate the stack from the scene layers (they read as one
  list before), and the licence indicator uses the creator's wording — `STEAM ID NOT PRESENT` /
  `Steam ID Limit: 30fps` / `Click for More Info`, becoming `STEAM ID PRESENT` / `60fps` with a close
  control once owned.

Tests: `StreamRecoveryTests` (schedule, recover on attempt 2 with the pipe restarted each time,
complete-broadcast honesty, unknown liveness, give-up, cancel, audio-restart fault),
`FramePumpTests` now pin that process death raises `EncoderFailed` and not `Failed`.
FAST gate: 538 passed (one documented pre-existing audio failure), 0 warnings.

ytLive.Tests/AttentionAlertStackTests.cs

@@ -32,15 +32,15 @@ public sealed class AttentionAlertStackTests
             vm.EntitlementOverride = new FakeEntitlement(false, "Steam licensing is not configured in this build.");
 
             var row = Assert.Single(vm.AttentionAlerts);
-            Assert.Equal("STEAM LICENCE", row.Label);
+            Assert.Equal("STEAM ID NOT PRESENT", row.Label);
             Assert.True(row.IsPinned);
             Assert.True(row.ShowsPin);
             Assert.False(row.CanDismiss);
             Assert.Equal(AttentionAlertAction.About, row.Action);
 
-            // A status readout: what this build is entitled to, and the maximum.
-            Assert.Contains("Entitlement 30 fps", row.Text);
-            Assert.Contains("Maximum 60 fps", row.Text);
+            // Creator wording: the limit this build runs at, and where to find out why.
+            Assert.Contains("Steam ID Limit: 30fps", row.Text);
+            Assert.Contains("Click for More Info", row.Text);
             Assert.DoesNotContain("unavailable", row.Text, StringComparison.OrdinalIgnoreCase);
         });
     }
@@ -56,18 +56,18 @@ public sealed class AttentionAlertStackTests
             Assert.False(row.IsPinned);
             Assert.False(row.ShowsPin);
             Assert.True(row.CanDismiss);
-            Assert.Contains("Entitlement 60 fps", row.Text);
+            Assert.Contains("Steam ID Limit: 60fps", row.Text);
 
             vm.DismissAlertCommand.Execute(row);
             Assert.Empty(vm.AttentionAlerts);
 
             // Permanent: a fresh view-model on the same profile must not bring it back…
             var reloaded = new MainViewModel();
-            Assert.DoesNotContain(reloaded.AttentionAlerts, alert => alert.Label == "STEAM LICENCE");
+            Assert.DoesNotContain(reloaded.AttentionAlerts, alert => alert.Label.StartsWith("STEAM ID"));
 
             // …but losing ownership restores it as a pinned indicator: a change of state, not a preference.
             reloaded.EntitlementOverride = new FakeEntitlement(false, "Steam licensing is not configured in this build.");
-            var restored = reloaded.AttentionAlerts.First(alert => alert.Label == "STEAM LICENCE");
+            var restored = reloaded.AttentionAlerts.First(alert => alert.Label == "STEAM ID NOT PRESENT");
             Assert.True(restored.IsPinned);
         });
     }
@@ -89,10 +89,11 @@ public sealed class AttentionAlertStackTests
     {
         WithVm(vm =>
         {
+            vm.EntitlementOverride = new FakeEntitlement(false, "Steam licensing is not configured in this build.");
             vm.PushAttentionAlertForTest("drop-1", "STREAM", "Stream dropped — reconnecting (attempt 1 of 4)", 10, 12);
             vm.PushAttentionAlertForTest("drop-2", "STREAM", "Stream dropped — reconnecting (attempt 2 of 4)", 13, 15);
 
-            Assert.Equal(new[] { "STEAM LICENCE", "STREAM", "STREAM" }, vm.AttentionAlerts.Select(a => a.Label));
+            Assert.Equal(new[] { "STEAM ID NOT PRESENT", "STREAM", "STREAM" }, vm.AttentionAlerts.Select(a => a.Label));
             // Newest event sits directly under the indicator.
             Assert.Contains("attempt 2", vm.AttentionAlerts[1].Text);
             Assert.Contains("attempt 1", vm.AttentionAlerts[2].Text);
@@ -104,7 +105,7 @@ public sealed class AttentionAlertStackTests
 
             vm.DismissAlertCommand.Execute(vm.AttentionAlerts[1]);
             Assert.Equal(2, vm.AttentionAlerts.Count);
-            Assert.Equal("STEAM LICENCE", vm.AttentionAlerts[0].Label);
+            Assert.Equal("STEAM ID NOT PRESENT", vm.AttentionAlerts[0].Label);
         });
     }