edge_weights does not reflect edges added after construction

[sgrava]

edge_weights does not reflect edges added after construction

Description

DataGraph._edge_weights is populated by _reset_dicts(), which is called only at construction time. Since add_edges_from is inherited from NetworkX and does not update _edge_weights, any edges added after construction are missing from edge_weights with no error or warning.

Root cause

BaseGraph._reset_dicts seeds _edge_weights from sorted_edges once, at construction. Subsequent add_edges_from calls go directly to the NetworkX layer and bypass _reset_dicts.
Minimum reproducible example

from qoolqit.graphs.data_graph import DataGraph

g = DataGraph.from_nodes([0, 1, 2])
g.add_edges_from([(0, 1), (1, 2)])

print(g.edge_weights)  # {} — expected {(0, 1): None, (1, 2): None}

Expected behaviour
{(0, 1): None, (1, 2): None}