Clean up Alembic migrations

- Removed outdated and redundant Alembic migration files to streamline the migration directory. This improves maintainability and eliminates duplicate or unused scripts.

backend/app/models/oauth_authorization_code.py

@@ -24,6 +24,9 @@ class OAuthAuthorizationCode(Base, UUIDMixin, TimestampMixin):
     - Must validate redirect_uri matches exactly
     - Must verify PKCE code_verifier for public clients
     - Must be consumed within expiration time
+
+    Performance indexes (defined in migration 0002_add_performance_indexes.py):
+    - ix_perf_oauth_auth_codes_expires: expires_at WHERE used = false
     """
 
     __tablename__ = "oauth_authorization_codes"

backend/app/models/oauth_provider_token.py

@@ -27,6 +27,9 @@ class OAuthProviderRefreshToken(Base, UUIDMixin, TimestampMixin):
     - Support token rotation (new refresh token on use)
     - Track last used time for security auditing
     - Support revocation by user, client, or admin
+
+    Performance indexes (defined in migration 0002_add_performance_indexes.py):
+    - ix_perf_oauth_refresh_tokens_expires: expires_at WHERE revoked = false
     """
 
     __tablename__ = "oauth_provider_refresh_tokens"

backend/app/models/organization.py

@@ -10,6 +10,9 @@ class Organization(Base, UUIDMixin, TimestampMixin):
     """
     Organization model for multi-tenant support.
     Users can belong to multiple organizations with different roles.
+
+    Performance indexes (defined in migration 0002_add_performance_indexes.py):
+    - ix_perf_organizations_slug_lower: LOWER(slug) WHERE is_active = true
     """
 
     __tablename__ = "organizations"

backend/app/models/user.py

@@ -6,6 +6,14 @@ from .base import Base, TimestampMixin, UUIDMixin
 
 
 class User(Base, UUIDMixin, TimestampMixin):
+    """
+    User model for authentication and profile data.
+
+    Performance indexes (defined in migration 0002_add_performance_indexes.py):
+    - ix_perf_users_email_lower: LOWER(email) WHERE deleted_at IS NULL
+    - ix_perf_users_active: is_active WHERE deleted_at IS NULL
+    """
+
     __tablename__ = "users"
 
     email = Column(String(255), unique=True, nullable=False, index=True)

backend/app/models/user_organization.py

@@ -44,7 +44,7 @@ class UserOrganization(Base, TimestampMixin):
         Enum(OrganizationRole),
         default=OrganizationRole.MEMBER,
         nullable=False,
-        index=True,
+        # Note: index defined in __table_args__ as ix_user_org_role
     )
     is_active = Column(Boolean, default=True, nullable=False, index=True)
 

backend/app/models/user_session.py

@@ -22,6 +22,9 @@ class UserSession(Base, UUIDMixin, TimestampMixin):
 
     Each time a user logs in from a device, a new session is created.
     Sessions are identified by the refresh token JTI (JWT ID).
+
+    Performance indexes (defined in migration 0002_add_performance_indexes.py):
+    - ix_perf_user_sessions_expires: expires_at WHERE is_active = true
     """
 
     __tablename__ = "user_sessions"