Addresses #2147

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Adds robust retry handling for Supabase API interactions to reduce
flakiness on HTTP 429.
> 
> - Introduces `RateLimitError`, `isRateLimitError`,
`retryWithRateLimit` (defaults: 6 retries, 2s base, capped, jitter,
scoped logging) and `fetchWithRetry`
> - Applies retries to key callsites: project API keys, schema/queries,
secrets, orgs/members/details, projects, project logs, branches,
function deploy/delete, bulk update, and SQL execution
> - Standardizes non-429 fetch failures to throw
`SupabaseManagementAPIError` to preserve response context
> - Improves function deploy by rebuilding `FormData` per attempt and
converting 429 to `RateLimitError`
> - Adds thorough unit tests covering error detection, backoff behavior,
options, and retry exhaustion
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
eaf86cffb2d2b3a3771e8607a52f4e04af630ecd. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Add automatic retries for Supabase API calls on HTTP 429 using
exponential backoff with jitter to reduce flakiness and improve
reliability. Addresses #2147 by applying retries across key management
and context callsites and adding thorough tests.

- **New Features**
- Added retryWithRateLimit (defaults: 8 retries, 2s base delay, 30s max,
10% jitter, scoped logging), isRateLimitError, RateLimitError, and
fetchWithRetry.
- Applied retries to fetch-based endpoints and runQuery operations:
orgs/members/details/projects, project logs, schema/table/function
queries, secrets/API keys, branches, function deploy/delete and bulk
update, and SQL execution.
- Standardized error handling by throwing SupabaseManagementAPIError for
failed fetches to preserve response details.
- Added unit tests covering detection, backoff timing, options, retry
exhaustion, and fetchWithRetry behavior.

<sup>Written for commit c1fbffaf9c559c7f43a6999f4160a81b97ed9eaf.
Summary will update on new commits.</sup>

<!-- End of auto-generated description by cubic. -->