P1D.2D: bring Phasor workstation to ArdIrec parity

[masarray]

Stacked on P1D.2C PR #298. Keep this draft and unmerged until the lower P1D stack is rebased onto merged engine/application heads and field validation is complete.

P1D.2D is the Phasor workstation-parity slice. It ports ArdIrec's mature record-level phasor workflow into the native WPF COMTRADE workspace without duplicating DFT math in managed code.

Implemented here:

• Phasor is now record-level rather than selected-row-dependent;
• Voltage and Current phasor diagrams render simultaneously with independent radial scales, avoiding dimensional comparison between V and A;
• both diagrams use the same global C1/C2 investigation reference and the same native one-cycle ArdIrec phasor export;
• compact C1/C2 selector is shown only in Phasor mode; Time Signals remains the cursor-position authority;
• reference header reports the actual source frame and trigger-relative time;
• channel selection uses ArdIrec P1D.2A role/phase semantics when available;
• one coherent same-circuit + same-unit phase family is chosen per Voltage/Current panel, with dimension-safe same-unit fallback for sparse circuit metadata;
• phase ordering is L1/L2/L3/E and duplicate channels for one phase are not mixed into the diagram;
• Phasor stays available even when the selected signal row is digital, because the view is record-level;
• Harmonics remains selected-channel/C1 behavior and is intentionally not redesigned in this slice;
• pure tests cover phase ordering, Voltage/Current separation, coherent circuit selection, unit safety, duplicate-phase handling, and canonical phase mapping.

P1D.2B Measurement Panel / global representation UI remains separate. This slice consumes the global C1/C2 timeline established by P1D.2C but does not duplicate the pending measurement presentation layer.

Exact-head validation

Qualified head: eb4b35c31f367d829ff4e6115e2753182f932521

• Build ARSAS #2376 — SUCCESS (solution build/regressions, portable publish and smoke)
• Validate SV evidence bundles #1386 — SUCCESS
• Validate COMTRADE viewer integration Add production attestation and consent-first privacy controls #85 — SUCCESS (pinned ArdIrec build/test/stage + native bridge/runtime verification)
• Validate ARSAS Windows installer #807 — SUCCESS (solution build/test, pinned ArdIrec staging, real managed bridge fixture, installer compile, silent install/uninstall smoke, checksum/artifact)
• Installer artifact: ARSAS-1.6.35-win-x64-installer, artifact 10133514606, SHA-256 8daa2ae1f6e038f11c2d4d34f7f64eb92c82769ae30d124fc942838b6e1ade68
• Pinned P1D.2A ArdIrec head b611a6c6ab9262d0e1cc50fdf6fc76910d90d298 is independently green on CI, CodeQL and Windows Build.

PR remains DRAFT + UNMERGED because it is stacked on #298/#297/#295 and the temporary ArdIrec P1D.2A pin must be replaced with merged engine main before landing.