`_load_graph` forces `directed: True` so renderers can recover stored arc
order (#2309), and `_bfs`/`_dfs` expand through `G.neighbors()`, which on a
DiGraph yields successors only. Seeded on a leaf that is only ever called,
imported and contained, the MCP `query_graph` therefore answered with the
seed alone, while the CLI `query` — which loads the same graph.json
undirected on purpose (#2080) — returned the callers, the test and the
neighbouring modules. Same shape as #1174: one read surface missed a fix
the others got.
Add `_traversal_view`: an undirected copy for the traversal with `_src`/
`_tgt` stashed per edge, so `_subgraph_to_text` keeps rendering
caller->callee regardless of the side the traversal reached the edge from.
An undirected input is returned as-is, so the CLI path is unchanged;
`_load_graph` is untouched because `get_neighbors` and `shortest_path`
rely on direction explicitly.
Regression tests seed the same `calls` edge from both endpoints through
`_load_graph`, in both traversal modes, with and without a context filter;
the callee-seeded ones fail on the prior code with `1 nodes found`.
(cherry picked from commit 341aec5286)
