quak backup retries failed requests for longer (closes #165)

src/retry.ts exports UNATTENDED_RETRY_OPTIONS beside the unchanged
default: 10 attempts, a 1 s base delay and a 60 s cap, so a request that
keeps failing waits at most 243 s before it gives up. bin/quak.ts loads
the backup's session with them, so its refresh, ML data and downloads
all use them; every other command keeps the default. What is retried
and the backoff formula are unchanged.

Model: opus-5-5

test/retry/retry.test.ts

@@ -43,6 +43,7 @@ import {
     isRetryable,
     isSafeToReplay,
     resolveRetryOptions,
+    UNATTENDED_RETRY_OPTIONS,
     withRetry,
 } from "../../src/retry.js";
 import { ApiError, TruncatedStreamError } from "../../src/errors.js";
@@ -639,3 +640,33 @@ describe("retry defaults", () => {
         }
     });
 });
+
+describe("unattended retry options", () => {
+    it("allow ten attempts, a 1 s base delay and a 60 s cap", () => {
+        // The numbers the README documents for `quak backup`.
+        expect(UNATTENDED_RETRY_OPTIONS.attempts).toBe(10);
+        expect(UNATTENDED_RETRY_OPTIONS.baseDelayMs).toBe(1_000);
+        expect(UNATTENDED_RETRY_OPTIONS.maxDelayMs).toBe(60_000);
+    });
+
+    it("give up on a request that keeps failing after at most 243 s of waiting", async () => {
+        // `random: () => 1` makes every wait its ceiling, the worst case.
+        const { sleep, delays } = recordingSleep();
+        let calls = 0;
+        await expect(
+            withRetry(
+                () => {
+                    calls++;
+                    return Promise.reject(new ApiError("HTTP 503", 503));
+                },
+                { ...UNATTENDED_RETRY_OPTIONS, sleep, random: () => 1 },
+            ),
+        ).rejects.toThrow("HTTP 503");
+
+        expect(calls).toBe(10);
+        expect(delays).toEqual([
+            1_000, 2_000, 4_000, 8_000, 16_000, 32_000, 60_000, 60_000, 60_000,
+        ]);
+        expect(delays.reduce((sum, ms) => sum + ms, 0)).toBe(243_000);
+    });
+});