test(bench): add a separate GDC FinBench Transaction suite

[DecisionNerd]

Objective

Integrate GDC FinBench Transaction as a separate suite.

Requirements

• Pin spec, Datagen, driver, parameters, dataset, and validation identities.
• Map only semantically supported operations to public interfaces.
• Keep reporting distinct from SNB, Graphalytics, and Graph500.

Acceptance criteria

• Tiny fixture validates load, mapping, and expected results.
• Transaction semantics and unsupported behavior are explicit.
• Evidence distinguishes correctness, resource, and harness failures.

BDD completion scenario

Given a pinned fixture
When supported operations run
Then results satisfy official validation semantics
And unsupported guarantees fail visibly.

Remaining completion evidence (2026-09-04)

Reopened after independent verification against main 905f2c5d: the existing suite does not yet execute the trusted live public GraphForge path proposed in #1085. Static/reference replay alone does not establish the public-path execution required above. Complete and review existing PR #1085, then verify the cumulative suite against every original acceptance criterion, including explicit unsupported semantics and truthful provenance/resource evidence. This note does not reduce workload coverage or turn a bounded live example into a full-suite claim. #952 remains the M11 completion gate.