Add admin panel with member management and password reset

Features:
- Admin panel at /settings/members for workspace owners
- View all workspace members with roles and last login
- Create new users directly (with temporary password)
- Change member roles (Owner/Editor/Viewer)
- Reset user passwords (forces change on next login)
- Remove members from workspace
- Force password reset flow on login
- Track last login timestamp for users

API Routes:
- GET/POST /api/workspaces/[id]/members
- GET/PATCH/DELETE /api/workspaces/[id]/members/[memberId]
- POST /api/workspaces/[id]/members/[memberId]/reset-password
- POST /api/auth/change-password

Schema changes:
- Added lastLoginAt DateTime? to User model
- Added forcePasswordReset Boolean to User model

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/app/login/page.tsx

@@ -34,6 +34,14 @@ function LoginForm() {
         return
       }
 
+      // Check if user needs to change password
+      if (data.forcePasswordReset) {
+        showToast('Please change your password to continue', 'info')
+        router.push('/change-password')
+        router.refresh()
+        return
+      }
+
       showToast('Welcome back!', 'success')
       // If there's a redirect param (e.g., from invite link), go there
       router.push(redirectTo || '/today')