…h rate limit (#3475)

## Summary

- Adds admin-only editors on the back-office org page for
`Organization.maximumProjectCount` and
`Organization.batchRateLimitConfig`, alongside the existing API rate
limit editor.
- Splits the back-office org page into per-section components
(`ApiRateLimitSection`, `BatchRateLimitSection`, `MaxProjectsSection`)
so each tool is self-contained — adding new sections later doesn't bloat
the route.
- Generalizes the rate-limit form into a reusable `RateLimitSection`
component + `RateLimitDomain` server config so API and batch share the
same UI, validation, and action handler. Each domain only owns its env
defaults, DB column, and logger key.
- "Saved." banner and validation errors are scoped to the section that
submitted, not the page.

Heads-up: the API rate-limit log key was renamed
`admin.backOffice.rateLimit` → `admin.backOffice.apiRateLimit` for
symmetry with the new `admin.backOffice.batchRateLimit`.

## Test plan

- [ ] As an admin, visit `/admin/back-office/orgs/:orgId` and confirm
all three sections render with the org's current values (or system
defaults).
- [ ] Edit and save each section; confirm only that section shows the
"Saved." banner.
- [ ] Submit invalid input (e.g. `0` tokens, malformed interval);
confirm errors render in the offending form only and the other sections
stay closed.
- [ ] Confirm a non-admin user is redirected away from the route.
- [ ] After saving a rate-limit override, hit the org with traffic and
confirm the new limit is enforced (API rate limit + batch rate limit
code paths read the column at request time).