fix(pipeline): make the complexity pass independent of worker id order

[DeusData]

Summary

The complexity pass (transitive_loop_depth / recursive) walked Function and Method nodes in temp-id order and each node's CALLS targets in adjacency order. Under parallel extraction the temp ids come from one shared atomic counter, so id order is worker-scheduling order and differs run to run. The cycle guard flags whichever member of a mutual-recursion cycle the DFS enters first, so recursive flipped between the members of a cycle across otherwise identical multi-worker runs while the CALLS edge set stayed identical -- a violation of the MT-byte-identical invariant.

Evidence

On a 66-file Python fixture of equal-sized mutual-recursion cycles (24 pairs + 6 triangles, adjacent in the size-ordered work queue) a probe saw 3 distinct outputs in 5 runs at 4 workers. The new regression test is RED on main 5/5 -- a 4-worker run diverges from the single-threaded run on the first cycle every time (p00_a.pair00_a "recursive":false vs true) -- and GREEN with this change.

Fix

Order the traversal by content only: seeds sorted by (qualified_name, file_path, start_line), and each node's CALLS targets sorted the same way before recursing, through one bump-stack scratch sized to the CALLS edge count (a single upfront allocation that bails the way the existing calloc path does). Semantics are unchanged: the DFS entry node of a cycle is the one flagged, as before; which member that is now depends on the inputs alone, identically for sequential and parallel indexing. SCC-based marking of every cycle member is out of scope here.

Test

pipeline_complexity_props_independent_of_worker_order (SUITE(pipeline), next to the sequential/parallel parity test) copies tests/fixtures/complexity_pass_cycle_order into a temp repo, indexes it once single-threaded and six times with CBM_WORKERS=4 through the same harness, collects every Function's complexity props sorted by qualified_name, and asserts all parallel runs are identical to the sequential run. Deterministic, no timing.

Verification

• build/c/test-runner pipeline complexity extraction (ASan/UBSan): 617 passed, 0 failed
• revert-check: RED 5/5 on main (production file reverted, rebuilt), GREEN with the fix
• make -f Makefile.cbm lint-ci: cppcheck + clang-format + NOLINT check clean
• scripts/check-no-test-skips.sh: OK; no raw fopen(, no SKIP/NOLINT, ASCII-only additions

Distilled from #1925 with co-author credit to @zhiyuzhang001-a11y.

Refs #1925