Fixes#13752
Removes the standalone `working_hours` API endpoint instead of fixing
only the callback typo in `WorkingHoursController`.
## Why
The route is not used by the dashboard. The supported product flow
already updates business hours through `PATCH
/api/v1/accounts/:account_id/inboxes/:id`.
The standalone endpoint was already unusable in practice:
- The controller callback pointed to the wrong method.
- Fixing that callback alone would still leave the endpoint blocked by
missing `WorkingHourPolicy` authorization.
- Keeping the route would preserve unsupported API surface without
making the product flow better.
## What this change does
- Removes `PATCH/PUT /api/v1/accounts/:account_id/working_hours/:id`.
- Deletes `Api::V1::Accounts::WorkingHoursController`.
- Leaves the inbox working-hours update path unchanged.
Compatibility note: this removes an undocumented endpoint that was
already unusable in practice. Working-hours updates should continue to
go through the supported inbox update API.
## Validation
- Ran `bin/rails routes -g working_hours` and confirmed the standalone
working-hours API route is no longer present.
- Searched for remaining `WorkingHoursController` and `resources
:working_hours` references.
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Co-authored-by: easonysliu <easonysliu@tencent.com>
Co-authored-by: Sojan Jose <sojan@pepalo.com>
