fix(extract): receiver-qualify Go method QNs

A Go method's QN was the flat package form (proj.pkg.method) — the
receiver was ignored, so every same-name method in a package collided
on one QN and the graph upsert kept exactly one node. Measured on a
real Go repo: 20 Process/Name methods across 15 files kept 2 nodes;
9 different Task() methods fused into one chimera node carrying all
nine bodies' call edges; 19 structs pointed DEFINES_METHOD at a single
shared method node; a _test.go mock Close outranked the production
Close in the dedupe tie-break. The upsert's own comment calls
kind-disambiguated QNs 'the real cure'.

Qualify the QN with the receiver type (proj.pkg.Recv.method), the same
shape as Go interface members and the C++ out-of-line method path
right below it in extract_func_def:

- extract_defs.c: def.qualified_name = parent_class + name whenever
  the receiver type resolves; go_receiver_type_name becomes the shared
  cbm_go_receiver_type_name (exported via helpers.h) so both sides of
  the contract use one formula.
- extract_unified.c (compute_func_qn): mirror branch for
  method_declaration, so method-body calls keep exact source
  attribution instead of degrading to File-node fallback
  (calls_find_source).
- Consumers already agree: pxc_build_lsp_def passes the def QN and
  parent_class (receiver_type) verbatim into the Go LSP registries,
  and check_go_class_implements explicitly supports class-qualified
  method QNs (its path (b)).

Side effect: resolve_same_module's exact module.name hash no longer
matches concrete methods, which kills the conf-0.9 false edges where
an interface-typed call bound to an unrelated same-package method.

Fixes #1909

Signed-off-by: Ilya Brykau <ilya.brykau@orca.security>

tests/test_parallel.c

@@ -3444,8 +3444,9 @@ TEST(parallel_go_cross_package_field_chain_resolves) {
     cbm_gbuf_t *gbuf = run_go_field_chain_sequential("go_field_fold", tmpdir, files, 2);
     ASSERT_NOT_NULL(gbuf);
 
-    const cbm_gbuf_edge_t *edge =
-        find_call_edge_to_target_fragment(gbuf, "handler.PlaceOrder", ".service.PlaceOrder");
+    /* Since #1909, Go method QNs are receiver-qualified on both endpoints. */
+    const cbm_gbuf_edge_t *edge = find_call_edge_to_target_fragment(
+        gbuf, "OrderHandler.PlaceOrder", ".service.OrderService.PlaceOrder");
     const bool found = edge != NULL;
     const bool dispatch = edge && edge->properties_json &&
                           strstr(edge->properties_json, "\"strategy\":\"lsp_type_dispatch\"");