## Summary
- Handle 403 Forbidden errors gracefully when listing Supabase branches
- Return empty array instead of throwing error for free tier users
without branch access
- Allows free tier users to continue using other Supabase features
without error toasts

Fixes #2525

## Test plan
- Verified all 784 unit tests pass
- Existing E2E test (`supabase_branch.spec.ts`) continues to work for
paid tier (test mode returns mock data)
- Free tier users should now see no branches available instead of an
error toast

🤖 Generated with [Claude Code](https://claude.com/claude-code)
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<!-- This is an auto-generated description by cubic. -->
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## Summary by cubic
Show a clear inline message when Supabase branch listing returns 403 for
free‑tier projects, and suppress error toasts so users can keep using
other Supabase features (addresses #2525).

- **Bug Fixes**
- Detect 403 from branches API and show “Branches are only supported for
Supabase paid customers” in the UI; no toast.
- Removed toast meta from the branches query and added getErrorMessage
to clean up IPC-wrapped errors.
  - Other statuses keep existing handling; paid tier behavior unchanged.

<sup>Written for commit eb414f84c5c4ff44a4f6f152aae5c395903430b3.
Summary will update on new commits.</sup>

<!-- End of auto-generated description by cubic. -->

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Co-authored-by: Will Chen <willchen90@gmail.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>