feat: API request/response logging with admin log viewer

- Add api_logs table (migration 0007) and ApiLog model
- Add web/lib/api_logger.py — httpx wrapper that records every outbound call
- Wire api_logger into vk_sync, vk_catalog, and connections test endpoints
- Add /admin/logs page with filters (service, method, status, time range, URL search) and expandable request/response detail
- Add "Логи" nav link for admin users

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/migrations/versions/0007_api_logs.py

@@ -0,0 +1,32 @@
+"""Add api_logs table for request/response logging."""
+revision = "0007"
+down_revision = "0006"
+branch_labels = None
+depends_on = None
+
+import sqlalchemy as sa
+from alembic import op
+
+
+def upgrade():
+    op.create_table(
+        "api_logs",
+        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),
+        sa.Column("service", sa.String(20), nullable=False),
+        sa.Column("method", sa.String(10), nullable=False),
+        sa.Column("url", sa.String(1024), nullable=False),
+        sa.Column("request_body", sa.Text, nullable=True),
+        sa.Column("response_status", sa.Integer, nullable=True),
+        sa.Column("response_body", sa.Text, nullable=True),
+        sa.Column("duration_ms", sa.Integer, nullable=True),
+        sa.Column("created_at", sa.DateTime, nullable=False, server_default=sa.func.now()),
+    )
+    op.create_index("ix_api_logs_user_service", "api_logs", ["user_id", "service"])
+    op.create_index("ix_api_logs_created_at", "api_logs", ["created_at"])
+
+
+def downgrade():
+    op.drop_index("ix_api_logs_created_at", "api_logs")
+    op.drop_index("ix_api_logs_user_service", "api_logs")
+    op.drop_table("api_logs")