Keep synced messages and events when removing a workspace member (#21443)

## Context

Removing a workspace member deletes their connected accounts, which
cascades into deleting every message and calendar event those accounts
synced. For a CRM, losing the email history of departed teammates is a
big deal.

## What this does

Connected accounts are now kept and reassigned instead of deleted when a
member is removed:

- Ownership moves to the acting user (whoever removed the member). When
members remove themselves (leave workspace, account deletion), it falls
back to the oldest admin.
- OAuth tokens are revoked, credentials wiped, message/calendar channels
get `isSyncEnabled = false`, and the account is stamped with a new
`archivedAt` column (fast instance command included).
- Synced messages, threads and calendar events stay in the workspace.
Channel visibility settings keep applying as before, since channels and
associations survive.
- The reassigned account appears in the new owner's Settings → Accounts,
where it can still be deleted (with its data) like any other account.

The transfer happens synchronously during removal, while the member's
userWorkspace row still exists. This also removes
`DeleteWorkspaceMemberConnectedAccountsCleanupJob` and its listener: the
async job had to reconstruct the account-owner link from rows the
removal flow had just deleted, which was race-prone (see 2181fb541e).

Archived accounts are excluded from the workflow send-email default
account resolution, and both removal confirmation modals now mention
what happens to synced data.

---------

Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>

packages/twenty-server/src/database/commands/upgrade-version-command/2-13/2-13-instance-command-fast-1781171103000-add-archived-at-to-connected-account.ts

@@ -0,0 +1,21 @@
+import { QueryRunner } from 'typeorm';
+
+import { RegisteredInstanceCommand } from 'src/engine/core-modules/upgrade/decorators/registered-instance-command.decorator';
+import { FastInstanceCommand } from 'src/engine/core-modules/upgrade/interfaces/fast-instance-command.interface';
+
+@RegisteredInstanceCommand('2.13.0', 1781171103000)
+export class AddArchivedAtToConnectedAccountFastInstanceCommand
+  implements FastInstanceCommand
+{
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(
+      'ALTER TABLE "core"."connectedAccount" ADD COLUMN IF NOT EXISTS "archivedAt" timestamptz',
+    );
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(
+      'ALTER TABLE "core"."connectedAccount" DROP COLUMN IF EXISTS "archivedAt"',
+    );
+  }
+}