feat: instance administration, bootstrap admin, and managed-tier OAuth gate

Self-hosted instances are now email/password only — OAuth providers
(GitHub/Google/Discord/Microsoft) activate solely when PRIMORA_MANAGED=true,
reserved for the future hosted tier.

Sign-up lifecycle: the first public sign-up becomes the instance admin; after
bootstrap, sign-up closes by default. A better-auth databaseHook gates only
/sign-up/email, so admin-created users and OAuth flows bypass it. The login
page reads GET /instance/public to hide the sign-up tab, show the bootstrap
notice, and render only the providers the instance offers.

Instance settings live in core.settings (migration 00010) and resolve
in-app > env > built-in default, cached 15s. Platform admins (better-auth
user.role) manage sign-up, mail transport, and rate limits via
GET/PUT/DELETE /instance/settings or the new Settings → Instance tab. Secret
values are AES-256-GCM encrypted at rest with PRIMORA_ENCRYPTION_KEY, never
returned by the API, and decrypted by the auth service at send time.

Auth service reads the same settings table for the sign-up gate and mail
config, so in-app changes take effect without a restart.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

packages/api-client/src/generated/services/InstanceService.ts

@@ -0,0 +1,88 @@
+/* generated using openapi-typescript-codegen -- do not edit */
+/* istanbul ignore file */
+/* tslint:disable */
+/* eslint-disable */
+import type { InstancePublicConfig } from '../models/InstancePublicConfig';
+import type { InstanceSetting } from '../models/InstanceSetting';
+import type { InstanceSettingsResponse } from '../models/InstanceSettingsResponse';
+import type { UpdateInstanceSettingRequest } from '../models/UpdateInstanceSettingRequest';
+import type { CancelablePromise } from '../core/CancelablePromise';
+import { OpenAPI } from '../core/OpenAPI';
+import { request as __request } from '../core/request';
+export class InstanceService {
+    /**
+     * Public instance state for the login page — no auth required
+     * @returns InstancePublicConfig Public instance configuration
+     * @throws ApiError
+     */
+    public static getInstancePublic(): CancelablePromise<InstancePublicConfig> {
+        return __request(OpenAPI, {
+            method: 'GET',
+            url: '/instance/public',
+        });
+    }
+    /**
+     * List instance settings (platform admin only)
+     * @returns InstanceSettingsResponse Resolved instance settings
+     * @throws ApiError
+     */
+    public static listInstanceSettings(): CancelablePromise<InstanceSettingsResponse> {
+        return __request(OpenAPI, {
+            method: 'GET',
+            url: '/instance/settings',
+            errors: {
+                401: `Error response`,
+                403: `Error response`,
+            },
+        });
+    }
+    /**
+     * Set an instance setting override (platform admin only)
+     * @returns InstanceSetting Setting stored
+     * @throws ApiError
+     */
+    public static updateInstanceSetting({
+        key,
+        requestBody,
+    }: {
+        key: string,
+        requestBody: UpdateInstanceSettingRequest,
+    }): CancelablePromise<InstanceSetting> {
+        return __request(OpenAPI, {
+            method: 'PUT',
+            url: '/instance/settings/{key}',
+            path: {
+                'key': key,
+            },
+            body: requestBody,
+            mediaType: 'application/json',
+            errors: {
+                400: `Error response`,
+                403: `Error response`,
+                404: `Error response`,
+            },
+        });
+    }
+    /**
+     * Revert a setting to its env/default value (platform admin only)
+     * @returns void
+     * @throws ApiError
+     */
+    public static deleteInstanceSetting({
+        key,
+    }: {
+        key: string,
+    }): CancelablePromise<void> {
+        return __request(OpenAPI, {
+            method: 'DELETE',
+            url: '/instance/settings/{key}',
+            path: {
+                'key': key,
+            },
+            errors: {
+                403: `Error response`,
+                404: `Error response`,
+            },
+        });
+    }
+}