fix(migrations): make 0110 safe for fresh installs

mail_accounts is a plugin table created after core migrations.
Wrap ALTER TABLE in DO $$ IF EXISTS block.

alembic/versions/0110_add_password_salt_to_mail_accounts.py

@@ -26,14 +26,27 @@ depends_on = None
 
 
 def upgrade() -> None:
+    # Only add the column if the mail_accounts table exists.
+    # On fresh installs, mail_accounts is created by the mail plugin's own
+    # migration (0001_initial.sql) which runs AFTER core alembic migrations.
     op.execute(
-        "ALTER TABLE mail_accounts "
-        "ADD COLUMN IF NOT EXISTS password_salt VARCHAR(64) NOT NULL DEFAULT ''"
+        "DO $$ "
+        "BEGIN "
+        "  IF EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name = 'mail_accounts') THEN "
+        "    ALTER TABLE mail_accounts "
+        "    ADD COLUMN IF NOT EXISTS password_salt VARCHAR(64) NOT NULL DEFAULT ''; "
+        "  END IF; "
+        "END $$"
     )
 
 
 def downgrade() -> None:
     op.execute(
-        "ALTER TABLE mail_accounts "
-        "DROP COLUMN IF EXISTS password_salt"
+        "DO $$ "
+        "BEGIN "
+        "  IF EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name = 'mail_accounts') THEN "
+        "    ALTER TABLE mail_accounts "
+        "    DROP COLUMN IF EXISTS password_salt; "
+        "  END IF; "
+        "END $$"
     )