Add subscription link field to user model

- Add subscription_link column to users table (nullable, unique)
- Add SUBSCRIPTION_URL to config settings
- Update user creation to include subscription link from Remnawave
- Add support subscription ticket creation with formatted message
- Add "update link" button to main menu
- Refactor support subscription formatting to include user details

alembic/versions/5985b2df0830_user_subscription_link_optional_text.py

@@ -0,0 +1,34 @@
+"""user -> +subscription_link optional text.
+
+Revision ID: 5985b2df0830
+Revises: 756210f564a5
+Create Date: 2026-04-09 20:38:15.157762
+
+"""
+
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision: str = "5985b2df0830"
+down_revision: Union[str, Sequence[str], None] = "756210f564a5"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.add_column("users", sa.Column("subscription_link", sa.TEXT(), nullable=True))
+    op.create_unique_constraint(None, "users", ["subscription_link"])
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_constraint(None, "users", type_="unique")
+    op.drop_column("users", "subscription_link")
+    # ### end Alembic commands ###