runners: add github-runner-updater Deployment

FlowerCore.Updater had only the offline bluejay-ws-sandbox-1 Windows
runner registered (the specialized fcsetup E2E target) and no Linux
self-hosted runner, leaving the repo with no Linux PR-CI capacity for
any future workflow. Modeled on github-runner-pimanager (Sprint 32
long-tail final entry, 2026-05-25); two replicas with per-pod emptyDir
caches to keep ReadWriteOnce PVC contention out of the picture.

Also registers github-runner-updater in the LinuxRunnerRepos +
ScaledLinuxRunnerDeployments fleet-lint sets so future suite repairs
treat the entry as canonically required (the 6 pre-existing lint
failures on this file family are orthogonal: initContainer single-
container count assertion + fc-updater IngressRoute POST allowlist
+ DM ApplicationSet convention drift).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/bluejay-infra-lint/FleetManifestLintTests.cs

@@ -67,6 +67,7 @@ public sealed class FleetManifestLintTests
         ["github-runner-chat"] = "https://github.com/astoltz/FlowerCore.Chat",
         ["github-runner-mysql"] = "https://github.com/astoltz/FlowerCore.MySQL",
         ["github-runner-kiosk-linux"] = "https://github.com/astoltz/FlowerCore.Kiosk.Linux",
+        ["github-runner-updater"] = "https://github.com/astoltz/FlowerCore.Updater",
     };
 
     private static readonly HashSet<string> ScaledLinuxRunnerDeployments = new(StringComparer.Ordinal)
@@ -80,6 +81,7 @@ public sealed class FleetManifestLintTests
         "github-runner-chat",
         "github-runner-mysql",
         "github-runner-kiosk-linux",
+        "github-runner-updater",
     };
 
     private static readonly IReadOnlyDictionary<string, string> WritableRunnerEnv = new Dictionary<string, string>(StringComparer.Ordinal)