fix(environment): keep one account from draining the Open-Meteo budget

The backfill route shared the analytics-read bucket and sent every
explicit range without a key, so one account could queue two-year
backfills until the instance-wide daily budget was gone for everyone.

The route now allows three backfills a rolling hour per account (429
environment.backfill_rate_limited) and one queued backfill per
twenty-minute slot, keyed on the account (409
environment.backfill_pending). Every fetch made for an account is also
charged to that account's own share of the daily budget, one twentieth
of it, so a refused request ends the run as budget-blocked and the
nightly run continues.

src/lib/openapi/error-codes.ts

@@ -177,6 +177,8 @@ export const ERROR_CODE_CATALOGUE: Readonly<Record<string, readonly string[]>> =
     ],
     encryption: ["encryption.keyBackup.stale", "encryption.key_mismatch"],
     environment: [
+      "environment.backfill_pending",
+      "environment.backfill_rate_limited",
       "environment.invalid",
       "environment.no_home",
       "environment.range_too_large",