fix(api): make alembic migrations idempotent for fresh databases

- 001: guard has_table check; skip if session_data already TEXT
- 002: guard each ADD COLUMN / CREATE TABLE; guard password migration
- 003: guard has_table; guard nullable check
- 004: guard has_table; skip if users.id already TEXT
- env.py: add Base.metadata.create_all after run_migrations to bootstrap fresh DBs
- api/user.py: make hashed_password nullable; add email_verified, image, email_inbound_token fields

Co-Authored-By: Paperclip <noreply@paperclip.ing>

alembic/versions/003_make_users_hashed_password_nullable.py

@@ -19,8 +19,25 @@ depends_on = None
 
 
 def upgrade() -> None:
-    op.alter_column("users", "hashed_password", existing_type=sa.String(255), nullable=True)
+    conn = op.get_bind()
+    inspector = sa.inspect(conn)
+
+    # Fresh DB — nothing to alter
+    if not inspector.has_table("users"):
+        return
+
+    cols = {c["name"]: c for c in inspector.get_columns("users")}
+    if "hashed_password" in cols and not cols["hashed_password"]["nullable"]:
+        op.alter_column("users", "hashed_password", existing_type=sa.String(255), nullable=True)
 
 
 def downgrade() -> None:
-    op.alter_column("users", "hashed_password", existing_type=sa.String(255), nullable=False)
+    conn = op.get_bind()
+    inspector = sa.inspect(conn)
+
+    if not inspector.has_table("users"):
+        return
+
+    cols = {c["name"]: c for c in inspector.get_columns("users")}
+    if "hashed_password" in cols and cols["hashed_password"]["nullable"]:
+        op.alter_column("users", "hashed_password", existing_type=sa.String(255), nullable=False)