fix(web): define high-score retry bounds

The browser storage plugin initializes and updates its high-score retry
backoff, but the constants supplying its initial and maximum delays were
lost during the merge that combined the retry and relative-endpoint fixes.
Define the intended 250 ms initial delay and 30 s cap so the plugin can load
and retain bounded retry behavior after transient submission failures.

Test Plan:
- `node --check tdkpin-rs/web/storage.js` -- passed
- Node VM top-level load harness -- passed
- `prettier --check tdkpin-rs/web/storage.js` -- passed
- `cargo +nightly fmt --all -- --check` -- passed
- `just test` -- passed (144 tests)
- `just clippy` -- passed
- `git diff --cached --check` -- passed

tdkpin-rs/web/storage.js

@@ -5,6 +5,8 @@
   const encoder = new TextEncoder();
   const decoder = new TextDecoder();
   const highScoreApi = "api/highscores";
+  const highScoreRetryInitialDelayMs = 250;
+  const highScoreRetryMaxDelayMs = 30_000;
   let lastRevision = 0;
   let lastHighScoreRevision = 0;
   let highScoreRequestInFlight = false;