Fixes #527 

<!-- CURSOR_SUMMARY -->
> [!NOTE]
> Enables org-scoped Supabase connectivity across the app with
per-organization tokens and org-aware project/branch/logs/function
operations.
> 
> - DB: migration `0019` adds `apps.supabase_organization_slug`; drizzle
schema updated
> - Settings/schema: introduce
`supabase.organizations{slug->{tokens,...}}`; helper
`isSupabaseConnected`; encrypt/decrypt per-org tokens
> - OAuth: `handleSupabaseOAuthReturn` now stores credentials under the
detected organization
> - IPC: new channels `supabase:list-organizations`,
`supabase:delete-organization`, `supabase:list-all-projects`; existing
branches/logs/set/unset handlers accept `organizationSlug`; preload
allowlist and ipc_client updated
> - Supabase management: clients selectable per organization; all calls
(projects, branches, logs, SQL, deploy/delete/bulk-update functions,
context/client code) accept `organizationSlug`
> - UI/hooks: `SupabaseConnector` and `SupabaseIntegration` list/manage
organizations, group projects by org, persist org on selection, and
handle org-scoped branch switching; `useSupabase` adds org state and
org-aware loaders; preview panel loads edge logs with org
> - Misc: AGENTS.md adds database/migrations guidance; minor test
fixture tweak
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
402bb2cd357dfd9c5d4de28ee68cb4719ca75a51. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->



















<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Adds multi-organization Supabase support so you can connect multiple
orgs, pick projects by org, and manage tokens per org. Updates UI,
settings, IPC, and the app schema to store organization context with
each connected project.

- **New Features**
- Connect multiple Supabase organizations; list, add, and delete
organizations.
- Project picker groups projects by organization; selection persists
organizationSlug on the app.
- Branch switching keeps the selected organization context; “Disconnect
Project” still works.
- Per-organization token storage and refresh; new IPC:
supabase:list-organizations, supabase:delete-organization,
supabase:list-all-projects.
- Settings shows connected organizations and “Disconnect All”; legacy
single-account flows continue to work.

- **Migration**
- Apply SQL migration 0019 to add supabase_organization_slug to the apps
table.

<sup>Written for commit 402bb2cd357dfd9c5d4de28ee68cb4719ca75a51.
Summary will update automatically on new commits.</sup>

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