fix(extract): receiver-qualify Go method QNs

[ilyabrykau-orca]

What does this PR do?

Fixes #1909. Stacked on #1907 (shares the Go test scaffolding in tests/test_extraction.c; the first commit here is #1907's — review only the last commit).

Go concrete methods carried a flat package QN (proj.pkg.method, receiver ignored), so every same-name method in a package collided on one QN and the graph upsert kept exactly one node — on the repo measured in #1909: 20 Process/Name methods → 2 nodes, 9 Task() methods fused into one chimera node carrying all nine bodies' call edges, 19 structs DEFINES_METHOD-linked to a single shared node, and a _test.go mock outranking the production method in the dedupe tie-break. The upsert's own comment calls kind-disambiguated QNs "the real cure".

The change — same shape as Go interface members and the C++ out-of-line method path directly below it in extract_func_def:

1. internal/cbm/extract_defs.c — when the receiver type resolves, def.qualified_name = parent_class + "." + name (proj.pkg.Storage.Close); go_receiver_type_name becomes the shared cbm_go_receiver_type_name (declared in helpers.h, following the cbm_cpp_out_of_line_parent_class precedent) so both sides of the contract use one formula.
2. internal/cbm/extract_unified.c (compute_func_qn) — mirror branch for Go method_declaration, so method-body calls keep exact source attribution instead of degrading to the calls_find_source File-node fallback.
3. No resolver changes needed — consumers already agree:
   • pxc_build_lsp_def passes the def QN and parent_class (→ receiver_type) verbatim into the Go LSP registries, so lsp_type_dispatch / lsp_embed_dispatch / interface-satisfaction emissions follow the new QN automatically (all lrp_go_s* probes stay GREEN, untouched).
   • check_go_class_implements explicitly supports class-qualified method QNs (its path (b) reconstructs <ClassQN>.<method>; its comment describes the flat QN as the anomaly).

Side effect (also #1909): resolve_same_module's exact module.name hash no longer matches concrete methods, which removes the confidence-0.9 false edges where an interface-typed call (pipeline.Process(event)) bound to an unrelated same-package method.

Tests:

• extract_go_method_receiver_qualified_qn — two same-name methods on different receivers get distinct, receiver-qualified QNs with matching parent_class; free functions keep the flat QN.
• extract_go_no_filename_in_module_qn updated: the method expectation becomes proj.myapp.db.Conn.Query (its actual contract — no filename segment in the QN — still asserted).
• Full scripts/test.sh leg green (ASan+UBSan, "All tests passed"), including all lsp_resolution_probe Go scenarios and the fix(pipeline): suppress weak short-name matches for Go selector calls #1907 pipeline test, with zero probe changes.

Note for maintainers: this changes extracted QNs for Go methods, so existing graphs need a reindex to pick up the new shape (flagged in #1909 per CONTRIBUTING's indexing-change rule).

Checklist

• Every commit is signed off (git commit -s) — required, CI rejects
  unsigned commits (DCO, see CONTRIBUTING.md)
• Tests pass locally (scripts/test.sh — full leg, ASan+UBSan, "All tests passed")
• Lint passes (git clang-format --diff clean on changed lines; clang-tidy/cppcheck via CI)
• New behavior is covered by a test (reproduce-first for bug fixes)

[github-actions]

Thanks for opening this — it has been seen, and it is queued.

This note is automated, but it is not a brush-off: it exists so you know where your PR stands instead of having to guess from silence.

Current review status: working through a backlog. 0.9.1-rc.1 is out, so the release freeze that held reviews is over — but it left a large queue of open pull requests behind it, and we are reading through them oldest-first. The background is in discussion #1144.

What that means for this PR, concretely:

• It will not be closed for inactivity. No stale bot touches pull requests here.
• It may still sit a while before a human reads it. That is on us, not on you.
• Older PRs are read first, so a recent one is not being skipped — it is behind a queue.

Things that will genuinely speed it up whenever review does happen:

• Keep it rebased on main — the tree is moving quickly right now, and a conflicting branch cannot be reviewed as the diff you intended.
• Get CI green, or say which failures you believe are pre-existing.
• Keep the change to one claim. Bundled features and refactors get split before they get merged, which costs you a round trip.
• Every commit needs a sign-off (git commit -s) — CI enforces DCO.

If this fixes a bug, a reproduction we can run is worth more than a description of the symptom.

Thanks for contributing, and sorry in advance for the wait.

[ilyabrykau-orca]

Rebased onto current main (stacked on the rebased #1907). No semantic changes; full test leg green. Post-fix field numbers for this change are in the #1906 census comment (method-node recovery incl. generic receivers: #1906 (comment)).