feat: integrate Etoplatezhi payment provider

- Add etoplatezhi_service.py with HMAC-SHA512+base64 signature algorithm,
  payment URL builder, and callback signature verification
- Add payment mixin with create/process/finalize flow, 12 status mappings
- Add CRUD operations with FOR UPDATE locking, idempotency checks
- Add Telegram handlers with SBP/Card sub-method selection
- Add Alembic migration for etoplatezhi_payments table
- Add config settings (ETOPLATEZHI_ENABLED, PROJECT_ID, SECRET_KEY,
  SBP_ENABLED, CARD_ENABLED, display names, min/max amounts)
- Add webhook endpoint with JSON-body signature verification
- Register in payment keyboard, router, utils, backup, method config

migrations/alembic/versions/0069_create_etoplatezhi_payments.py

@@ -0,0 +1,45 @@
+"""create etoplatezhi_payments table
+
+Revision ID: 0069
+Revises: 0068
+Create Date: 2026-05-04
+
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = '0069'
+down_revision: Union[str, None] = '0068'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        'etoplatezhi_payments',
+        sa.Column('id', sa.Integer(), primary_key=True, autoincrement=True),
+        sa.Column('user_id', sa.Integer(), sa.ForeignKey('users.id', ondelete='SET NULL'), nullable=True, index=True),
+        sa.Column('order_id', sa.String(64), unique=True, nullable=False, index=True),
+        sa.Column('etoplatezhi_payment_id', sa.String(128), unique=True, nullable=True, index=True),
+        sa.Column('amount_kopeks', sa.Integer(), nullable=False),
+        sa.Column('currency', sa.String(10), nullable=False, server_default='RUB'),
+        sa.Column('description', sa.Text(), nullable=True),
+        sa.Column('status', sa.String(32), nullable=False, server_default='pending'),
+        sa.Column('is_paid', sa.Boolean(), server_default=sa.text('false'), nullable=False),
+        sa.Column('payment_url', sa.Text(), nullable=True),
+        sa.Column('payment_method', sa.String(32), nullable=True),
+        sa.Column('metadata_json', sa.JSON(), nullable=True),
+        sa.Column('callback_payload', sa.JSON(), nullable=True),
+        sa.Column('paid_at', sa.DateTime(timezone=True), nullable=True),
+        sa.Column('expires_at', sa.DateTime(timezone=True), nullable=True),
+        sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.func.now()),
+        sa.Column('updated_at', sa.DateTime(timezone=True), server_default=sa.func.now()),
+        sa.Column('transaction_id', sa.Integer(), sa.ForeignKey('transactions.id'), nullable=True),
+    )
+
+
+def downgrade() -> None:
+    op.drop_table('etoplatezhi_payments')