feat: add App API deliverability methods — ESP suppressions & reporting webhooks

[mike-engel]

Yet another set of the App API backfill following #242 which adds 5 ESP email-suppression methods and 5 reporting-webhook methods to APIClient:

Method	Endpoint
searchSuppression	GET /v1/esp/search_suppression/{email}
getSuppressions	GET /v1/esp/suppression/{type}
getDomainSuppressions	GET /v1/esp/domains/{domain}/suppression/{type}
createSuppression	POST /v1/esp/suppression/{type}/{email}
deleteSuppression	DELETE /v1/esp/suppression/{type}/{email} (204)
listReportingWebhooks	GET /v1/reporting_webhooks
createReportingWebhook	POST /v1/reporting_webhooks
getReportingWebhook	GET /v1/reporting_webhooks/{id}
updateReportingWebhook	PUT /v1/reporting_webhooks/{id}
deleteReportingWebhook	DELETE /v1/reporting_webhooks/{id} (204)

Notes

• There is also a GET /v1/reporting_webhooks/{id}/errors endpoint (JS-webhook debugging) that the issue didn't scope; happy to add a getReportingWebhookErrors in a follow-up if useful.

Assisted by AI 🤖

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Note

Medium Risk
Large additive surface area with write paths (suppressions, webhooks, snippets, imports, metadata) that can affect deliverability and workspace data; behavior is thin HTTP wrappers with consistent validation.

Overview
Continues the App API client backfill on APIClient with a large set of new typed methods, matching the existing request/validation style (MissingParamError, buildQueryString, URL encoding).

Deliverability: ESP suppression search/list (global offset and per-domain cursor pagination), create/delete suppressions; full CRUD for reporting webhooks.

Content & operations: Snippet list/create/upsert/delete; sender identity list/get/used-by; workspace-wide message list/get/archived content with rich filters.

Data & account: CSV import create/status; batch attribute/event metadata updates; listWorkspaces and getIpAddresses.

docs/app.md documents all of the above. Unit tests in test/api.ts assert paths, query strings, and validation; test/integration/live.ts adds optional live coverage (including CIO_TEST_IMPORT_CSV_URL for imports).

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