refactor(spf): memoize Task.run via a named #execute, fixing orphan rejections

Memoize the run-machinery promise itself (`#promise ??= this.#execute()`) rather
than reassigning `#promise` to fresh `Promise.resolve(value)` / `Promise.reject(error)`
on settle. The reassigned promises were never awaited, so an errored or aborted
task that's not re-run (the norm — the RecurringRunner moves on to a clone) left
an unhandled rejection. The memoized promise is the one callers await, so it's
always handled.

Also closes a sync-throw gap: a `#runFn` that throws synchronously is now captured
as a rejected memoized promise instead of leaving `#promise` unset (which would
re-execute on the next run()).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/spf/src/core/tasks/task.ts

@@ -105,24 +105,28 @@ export class Task<TValue = void, TError = unknown> implements TaskLike<TValue, T
   }
 
   run(): Promise<TValue> {
-    // Memoized: run the work once; repeated calls share the same promise (which
-    // resolves/rejects immediately once settled). Re-running needs a `clone()`.
-    this.#promise ??= (async () => {
-      this.#status = 'running';
-      try {
-        const result = await this.#runFn(this.#signal);
-        this.#value = result; // value before status — ordering guarantee
-        this.#status = 'done';
-        return result;
-      } catch (e) {
-        this.#error = e as TError; // error before status — ordering guarantee
-        this.#status = 'error';
-        throw e;
-      }
-    })();
+    // Memoized: run the work once, sharing the same promise across calls. The
+    // memoized promise IS what callers await, so it's always handled (no orphan
+    // `Promise.resolve/reject`); a sync-throwing `#runFn` is captured as a
+    // rejection rather than re-run.
+    this.#promise ??= this.#execute();
     return this.#promise;
   }
 
+  async #execute(): Promise<TValue> {
+    this.#status = 'running';
+    try {
+      const result = await this.#runFn(this.#signal);
+      this.#value = result; // value before status — ordering guarantee
+      this.#status = 'done';
+      return result;
+    } catch (e) {
+      this.#error = e as TError; // error before status — ordering guarantee
+      this.#status = 'error';
+      throw e;
+    }
+  }
+
   abort(): void {
     this.#abortController.abort();
   }