feat(FN-3875): add GitHub tracking auth resolver and forced client auth mod

Implements a tracking auth resolver with forced GitHub client authentication mode, wiring it across the GitHub tracking lifecycle and settings UI. The feature spans six steps: adding the resolver, forced auth mode, routing tracking issue creation through the resolver, and wiring into lifecycle and s

Fusion-Task-Id: FN-3875

packages/dashboard/app/components/githubTracking.ts

@@ -1,4 +1,6 @@
-import { REPO_OVERRIDE_RE, type GlobalSettings, type ProjectSettings } from "@fusion/core";
+import type { GlobalSettings, ProjectSettings } from "@fusion/core";
+
+export const REPO_OVERRIDE_RE = /^[A-Za-z0-9._-]+\/[A-Za-z0-9._-]+$/;
 
 function normalizeRepoValue(value: string | null | undefined): string {
   const trimmed = value?.trim() ?? "";