fix: IMAP sync - use imap_uid, add sync queue with retry, restore deleted on sync, upload sent mails

- imap_delete_mail: use stored imap_uid instead of Message-ID search, raise on failure
- imap_move_mail: same imap_uid fix, raise on failure
- New MailSyncQueue model + migration 0007 for pending IMAP operations
- delete_mail route: queues failed IMAP delete for retry
- move_mail route: queues failed IMAP move for retry
- process_sync_queue: retries pending delete/move operations in auto-sync loop
- Auto-sync loop: processes sync queue before pulling new mails
- Restore soft-deleted mails if they still exist on IMAP server during sync
- Upload sent mails to IMAP Sent folder via APPEND after SMTP send
- Plugin version bumped to 1.2.0

app/plugins/builtins/mail/migrations/0007_sync_queue.sql

@@ -0,0 +1,17 @@
+-- Mail sync queue table for pending IMAP operations
+CREATE TABLE IF NOT EXISTS mail_sync_queue (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    mail_id UUID NOT NULL,
+    operation VARCHAR(50) NOT NULL,
+    payload JSONB NOT NULL DEFAULT '{}',
+    status VARCHAR(20) NOT NULL DEFAULT 'pending',
+    attempts INTEGER NOT NULL DEFAULT 0,
+    max_attempts INTEGER NOT NULL DEFAULT 3,
+    last_error TEXT,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX IF NOT EXISTS ix_mail_sync_queue_status ON mail_sync_queue (status);
+CREATE INDEX IF NOT EXISTS ix_mail_sync_queue_mail ON mail_sync_queue (mail_id);