feat: Update /admin to list/add/edit Organizers. Add "Change Organizer" to Events Dashboard. Clarify when "Overview" sidebar heading relates to Events -v- Organizer 🤖

[mrjbj]

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What changes I've made

1. Events Page: Reassign organizer

Two entry points, both end-user-facing (no superadmin needed):

• Change Organizer button positioned next to "Share Event" on event header. Opens a modal that mirrors the look of the existing SwitchOrganizerModal but performs an UpdateEvent mutation instead of navigating.
• Event Settings → Organizer dropdown Pre-filled with the current organizer; allows change to any organizers still active in the same account.

2. Superadmin /admin/organizers page

New entry in the admin sidebar between Users and Events, modelled directly on the existing admin Users page:

• Clicking a card navigates to /manage/organizer/{id} so the superadmin can use the existing organizer dashboard / settings flow to edit
• "Create Organizer" button reuses the existing CreateOrganizerModal. An info banner clarifies that creation is scoped to the superadmin's own account; to create in another account, impersonate a user there first.

3. Sidebar disambiguation

The sidebar group header Overview appeared identically on both the event sidebar and the organizer sidebar, with no visual cue of which scope you were in. Renamed:

• Event layout: Overview → Event Overview
• Organizer layout: Overview → Organizer Overview

Backend changes

File	Change
Services/Application/Handlers/Event/DTO/UpdateEventDTO.php	Added ?int $organizer_id = null
Http/Request/Event/UpdateEventRequest.php	Was actively unset-ing organizer_id; now ['sometimes', 'integer']
Services/Application/Handlers/Event/UpdateEventHandler.php	When organizer_id is set and differs from current, calls OrganizerFetchService::fetchOrganizer($id, $accountId) (existing service, same pattern as CreateEventHandler); throws OrganizerNotFoundException if cross-account
Http/Actions/Events/UpdateEventAction.php	Catches OrganizerNotFoundException → returns clean 422 with organizer_id field error
Models/Organizer.php	New account() belongsTo relationship
Repository/Eloquent/OrganizerRepository.php + interface	New getAllOrganizersForAdmin(?string $search, int $perPage): LengthAwarePaginator, eager-loads account and organizer_settings, search by name/email/account name
Http/Actions/Admin/Organizers/GetAllOrganizersAction.php (new)	Role::SUPERADMIN gated, identical structure to GetAllUsersAction
Services/Application/Handlers/Admin/GetAllOrganizersHandler.php + DTO (new)	Paginate via repo
Resources/Organizer/AdminOrganizerResource.php (new)	Includes nested account info
routes/api.php	New GET /admin/organizers route

Why I've made these changes

Today an event's organizer_id is set at creation and cannot be changed. There is no UI or API path to move an event between organizer brands within the same account.

I hit this in practice: I created an event while impersonating another user in my account, but the event landed under the default organizer (the one tied to my own user) rather than the organizer associated with the impersonated user's brand. The event's public page therefore showed the wrong brand. The only way to fix it was a direct DB update.

Separately, organizer management has poor discoverability — organizers only appear inside SwitchOrganizerModal, never as a dedicated page, and superadmins have no cross-account view of organizers analogous to the existing Users / Accounts / Events admin pages.

How I've tested these changes

Tests

backend/tests/Unit/Services/Application/Handlers/Event/UpdateEventHandlerTest.php (new) — 4 cases:

1. reassigns_organizer_when_organizer_id_provided_and_different
2. does_not_include_organizer_id_when_omitted (regression guard for previous behavior)
3. does_not_reassign_when_organizer_id_matches_current (no wasted writes)
4. rejects_cross_account_organizer (security boundary)

Full Unit suite: 357 passed, 0 failures (only the existing 1 deprecated + 1 skipped). Pint clean on all new files.

Translations

14 new strings, translated into 14 locales: de, es, fr, hu, it, nl, pl, pt, pt-br, se, tr, vi, zh-cn, zh-hk. ru intentionally untouched (matches existing project convention — that catalog is largely empty and the project does not require ru parity).

Checklist

• [x ] I have read the contributing guidelines.
• [x ] My code follows the coding standards of the project.
• [x ] I have tested my changes, and they work as expected.
• I understand that this PR will be closed if I do not follow the [contributor guidelines]
  (https://github.com/HiEventsDev/hi.events/blob/develop/CONTRIBUTING.md) and if this PR template is left unedited.