test: tag the untagged suites; correct two stale headers

Four test files and one node header carried no TRACES tag, so the
requirements they verify read as implemented-but-unverified. Tagging a
test is what distinguishes the two.

test_calibration.cpp is AR-023; its three [report] cases verify GR-003
and are tagged separately, since the report is fitted from the same
distributions but is its own requirement. test_similarity.cpp is the CI
half of AR-026 — equivalence against hand-computed dot products, where
throughput at scale is AR-027 and cannot run on this host.
test_face_tracker.cpp is AR-007 and AR-008.

Two headers described code that no longer exists. face_aligner_node.hpp
still documented the RANSAC fit AR-005 replaced with an Umeyama
least-squares fit over all five points — not merely out of date but the
opposite of what the file does, and it reads as a rationale for
discarding the landmarks AR-030 measures. test_face_tracker.cpp still
described the park/revive branch AR-008 deleted, and the raw-cosine
cut_revive_sim that guarded it, which AR-024 retired.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

TRACES: AR-005, AR-007, AR-008, AR-023, AR-026, AR-030 | GR-003 | SR-001, SR-002

tests/test_face_tracker.cpp

@@ -1,13 +1,17 @@
+// TRACES: AR-007, AR-008 | SR-002
+//
 // Unit tests for FaceTrackerFunc (nodes/face_tracker_node.hpp): frame-to-frame
 // track linking and, crucially, cross-cut re-association. Pure, GPU-free,
 // model-free — drives the node's operator() with hand-built EmbeddedSceneFrames
 // and inspects the emitted track_ids.
 //
-// The behaviour under test: on a camera-angle change (Frame::is_cut) the tracker
-// parks its tracks instead of destroying them, and revives a parked track_id
-// when a post-cut detection's raw last-frame-embedding cosine similarity clears
-// cut_revive_sim. IoU is deliberately driven to 0 across the cut (boxes moved) so
-// only the embedding path can re-link — exactly the scenario a cut creates.
+// The behaviour under test: there is one track pool keyed on `last_seen`
+// (AR-008), so a face lost across a camera-angle change (Frame::is_cut) is an
+// ordinary association candidate rather than a parked track needing a revival
+// path — the raw-cosine `cut_revive_sim` that guarded that path is retired
+// (AR-024). On a cut the association weight drops to embedding-only (AR-007),
+// and IoU is deliberately driven to 0 across the cut (boxes moved) so only the
+// embedding path can re-link — exactly the scenario a cut creates.
 #include <catch2/catch_test_macros.hpp>
 
 #include "config.hpp"