feat(dashboard): add MeDto, AdminDto, apiKeys + role/password helpers

Extends api.ts with the Phase 3.5 wire types (InstanceRole, Scope,
MeDto, AdminDto, ApiKeyDto, MintApiKey*) and the matching apiKeys
namespace. AdminUser in auth.ts now carries instance_role and email,
so layout/store consumers see the role without a separate fetch.

Adds two tiny lib helpers used by the upcoming profile/users pages:
RoleChip.svelte for the colored owner/admin/member pill, and
password-gen.ts for crypto.getRandomValues-backed temporary
passwords used in user-invite + reset-password reveals.

AdminUserRecord stays as a deprecated alias until /admins is
retired in a follow-up commit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

dashboard/src/lib/auth.ts

@@ -10,9 +10,13 @@
 import { writable, get } from 'svelte/store';
 import { browser } from '$app/environment';
 
+export type InstanceRole = 'owner' | 'admin' | 'member';
+
 export interface AdminUser {
 	id: string;
 	username: string;
+	instance_role: InstanceRole;
+	email: string | null;
 }
 
 const TOKEN_KEY = 'picloud.admin.token';