P1D.2A: validate latest ArdIrec investigation bridge from .NET

[masarray]

Stacked on ARSAS PR #295. This is a consumer-proof slice only; it does not change COMTRADE UX yet.

It temporarily pins the exact P1D.2A ArdIrec bridge head built on top of open ArdIrec PR #30 and adds managed integration coverage for the new investigation-context exports:

• capability probing;
• analog role/phase semantics;
• Primary/Secondary scaling metadata;
• cursor instantaneous + trailing one-cycle true RMS;
• normal-state-aware digital state;
• nearest digital-edge snap.

The test loads the exact ardirec_bridge.dll produced by the pinned engine in the integration/installer lanes and calls the C ABI directly, so P/Invoke struct layout/function signatures are proven before P1D.2B wires global C1/C2 and the measurement panel.

Do not merge this temporary pin. After ArdIrec P1D.2A lands, replace the lock with the merged main SHA and fold the managed wrapper changes into P1D.2B.

[masarray]

Superseded by the field-accepted consolidated COMTRADE integration in PR #300, squash-merged to main as c3e2ac3ef6e6a3a49f47c5155a0ba4a7c00bcb6b. The native dependency was also landed first via ArdIrec PR #41. Closing this temporary stacked consumer PR without a separate merge avoids duplicate history.