feat: firewall policy switches and nftables troubleshooting

- Add peer-to-peer and LAN-to-peers switches on the rules page
- Both settings persisted in configurations table and applied
  as nftables chains on toggle
- Add "View nftables Rules" button to dump the live ruleset
  for troubleshooting
- Rules page redesigned with card-based layout matching other
  admin pages
- Rule create/edit/delete events fire as background tasks

alembic/versions/b7e2f4a1c903_add_firewall_policy_fields.py

@@ -0,0 +1,28 @@
+"""add firewall policy fields to configurations
+
+Revision ID: b7e2f4a1c903
+Revises: a3f1d8e92b01
+Create Date: 2026-03-31 00:00:00.000000
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'b7e2f4a1c903'
+down_revision: Union[str, None] = 'a3f1d8e92b01'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column('configurations', sa.Column('allow_peer_to_peer', sa.Boolean(), nullable=False, server_default='false'))
+    op.add_column('configurations', sa.Column('allow_lan_to_peers', sa.Boolean(), nullable=False, server_default='false'))
+
+
+def downgrade() -> None:
+    op.drop_column('configurations', 'allow_lan_to_peers')
+    op.drop_column('configurations', 'allow_peer_to_peer')