docs: add CSV import limit guidance for bulk admin flows

Document operational expectations for CSV file-size and row-count limits during provider bulk-user import automation.

README.md

@@ -140,6 +140,7 @@ This wrapper now delegates to `BlackWall\Auth\AuthClient`.
 - For reverse-proxy deployments, harden trusted proxy/IP forwarding configuration to prevent spoofed client IP headers.
 - Keep client-side admin mutation retries idempotent; approval workflows can be lock-serialized and should not be assumed to execute twice.
 - Do not submit parallel approve/reject/cancel decisions for the same approval request ID.
+- Apply bounded CSV import sizes and row counts for admin bulk-user operations.
 - Never place client secrets, refresh tokens, or access tokens in URL query strings.
 - For OIDC providers, include a per-request `nonce` in authorisation requests.
 - For direct Cryptbin API usage, send `key_b64url` on unwrap calls; provider rejects key-mismatch unwrap attempts with `403 Forbidden`.

docs/INTEGRATION_GUIDE.md

@@ -159,6 +159,7 @@ Provider user/project assignment views may exclude disabled projects even if his
 - If your deployment runs behind reverse proxies, ensure trusted-proxy configuration is strict so spoofed forwarding headers cannot bypass IP-based abuse controls.
 - For approval-driven admin mutations, assume provider-side execution is serialized per approval item; client retries should still be idempotent and bounded.
 - This serialization applies across approval actions (approve/reject/cancel), so clients should avoid parallel decision submissions for the same request ID.
+- For provider CSV-based user import operations, enforce strict file-size and row-count limits in automation tooling and surface clear operator errors on limit breaches.
 - Configure OAuth client redirect URIs as HTTPS in production; reserve HTTP for localhost loopback testing only.
 - Assume provider rate limits are enforced per source identity (for example IP) and shared across related auth endpoints.
 - Treat report/export-style provider endpoints as high-cost and expect stricter rate limits.