[bug]: Show clear error when accepting workspace invite while signed in with wrong email

Is there an existing issue for this?

• I have searched the existing issues

Current behavior

When a user opens a workspace invitation link while signed in with a different email than the invite, POST /api/workspaces/<slug>/invitations/<id>/join/ returns 403:

{"error": "You do not have permission to accept this invitation"}

Expected

• Show a toast with the API error
• If emails don't match, show UI explaining the invite was sent to X but they are signed in as Y
• Offer "Sign out and switch account"
• Prevent repeated Accept clicks while a request is in flight

Actual

• apps/web/app/(all)/workspace-invitations/page.tsx only console.errors on failure
• No toast / no mismatch guidance
• User can spam Accept and see repeated 403s in the network tab with no visible message

Steps to reproduce

1. As Admin, invite user A (a@example.com) to a workspace and copy the invite link (with invitation_id, slug, token).
2. Sign in as user B (b@example.com).
3. Open the invite link: /workspace-invitations/?invitation_id=...&slug=...&token=...
4. Click Accept.
5. Observe: Network 403, console error object, no toast or on-screen explanation.

Environment

Deploy preview

Browser

Google Chrome

Variant

Local

Version

1.4.2