feat(FN-3868): add changeset for github tracking settings

Adds a changeset for the GitHub tracking settings feature (FN-3868), preparing it for the next release. The feature itself was implemented in earlier steps; this changeset marks it for publication to npm.

Fusion-Task-Id: FN-3868

packages/core/src/settings-validation.ts

@@ -1,6 +1,8 @@
-import type { UnavailableNodePolicy } from "./types.js";
+import type { GithubAuthMode, UnavailableNodePolicy } from "./types.js";
 
 const UNAVAILABLE_NODE_POLICIES: readonly UnavailableNodePolicy[] = ["block", "fallback-local"] as const;
+const GITHUB_AUTH_MODES: readonly GithubAuthMode[] = ["gh-cli", "token"] as const;
+const GITHUB_REPO_SLUG_PATTERN = /^[A-Za-z0-9._-]+\/[A-Za-z0-9._-]+$/;
 
 /**
  * Validates a project unavailable-node routing policy value.
@@ -18,3 +20,29 @@ export function validateUnavailableNodePolicy(value: unknown): UnavailableNodePo
     ? (value as UnavailableNodePolicy)
     : undefined;
 }
+
+/** Returns a validated GitHub auth mode for project settings, otherwise undefined. */
+export function validateGithubAuthMode(value: unknown): GithubAuthMode | undefined {
+  if (value === undefined) {
+    return undefined;
+  }
+  if (typeof value !== "string") {
+    return undefined;
+  }
+  return (GITHUB_AUTH_MODES as readonly string[]).includes(value) ? (value as GithubAuthMode) : undefined;
+}
+
+/** Returns a validated owner/repo GitHub slug, otherwise undefined. Empty string is treated as unset. */
+export function validateGithubRepoSlug(value: unknown): string | undefined {
+  if (value === undefined) {
+    return undefined;
+  }
+  if (typeof value !== "string") {
+    return undefined;
+  }
+  const trimmed = value.trim();
+  if (trimmed.length === 0) {
+    return undefined;
+  }
+  return GITHUB_REPO_SLUG_PATTERN.test(trimmed) ? trimmed : undefined;
+}