## What
Wires the existing (mocked) Platform Webhooks UI to the real Management
API backend, per FE-3749.
- New `data/platform-webhooks/` query/mutation hooks, calling the real
`/v2/organizations/{slug}/webhooks/...` and
`/v2/projects/{ref}/webhooks/...` endpoints
- Updated `PlatformWebhooks.types.ts` to match the real API contract
(field names, shapes)
- Added a signing secret field to the create-endpoint form (API requires
a user-provided secret, not server-generated like the mock assumed)
- Removed the event-type column from the deliveries table (the real
list-deliveries endpoint doesn't return event type, only the
single-delivery endpoint does)
- Removed `PlatformWebhooks.mock.ts` / `.store.ts` and their tests
## Why
UI was built ~80% against mock data months ago; this closes the gap to a
real, working feature.
## Known open items (not blocking, tracked separately)
- `name` field has no backend storage yet — client-only for now, open
question with Ali/Paweł
- Deliveries table only fetches the backend's default single page — real
server-side pagination not yet wired (see FE-3750)
## Follow-up PR (stacked)
Tests for the new `data/platform-webhooks/` hooks (MSW-based), per the
ticket's own scope split.
## Testing
Manually tested end-to-end against local backend: created/edited/deleted
an endpoint, verified the real signature using webhook.site,
independently recomputed the HMAC and confirmed it matches the
`webhook-signature` header.
Linear: FE-3749
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Co-authored-by: Charis Lam <26616127+charislam@users.noreply.github.com>