fix(FN-5089): add trailer settings typing defaults

Fusion-Task-Id: FN-5089
Fusion-Task-Lineage: ad7ea32a-c024-45bb-b68e-b65665b9b7c6

packages/core/src/settings-schema.ts

@@ -215,6 +215,7 @@ export const DEFAULT_PROJECT_SETTINGS = {
   },
   worktreesDir: undefined,
   taskPrefix: "FN",
+  taskAttributionTrailerNames: ["Fusion-Task-Id"],
   commitMsgHookEnabled: true,
   includeTaskIdInCommit: true,
   commitAuthorEnabled: true,

packages/core/src/types.ts

@@ -2724,6 +2724,10 @@ export interface ProjectSettings {
    *  Defaults to `"KB"`. Only affects new tasks — existing tasks retain
    *  their original IDs. */
   taskPrefix?: string;
+  /** Preferred commit trailer keys for task attribution in priority order.
+   *  The first value is used by commit-msg hook installation when enabled.
+   *  Defaults to `["Fusion-Task-Id"]`. */
+  taskAttributionTrailerNames?: string[];
   /** When true, Fusion installs a commit-msg hook in managed task worktrees
    *  that appends the configured task attribution trailer (e.g. `Fusion-Task-Id: FN-123`).
    *  Set to false for projects with custom hook infrastructure. Default: true. */