[Transformation] Preserve synthesized global phase through controlled helper lowering

[cabreraam]

Warning

This PR depends on #4976, #5022, #5044, #5058, and #5062, so it shouldn't be reviewed until each of those PRs has been upstreamed.

Summary

Preserve the global phase factored out during unitary synthesis as quake.phase, so it remains available when a synthesized helper is later invoked under control.

Previously, ZYZ and KAK synthesis encoded the correction e^(iφ) I as:

quake.r1 (2φ) %target
quake.rz (-2φ) %target

This PR emits the canonical quake.phase representation instead, allowing apply-op specialization to propagate an outer control to the phase correction.

Implementation

• Update UnitarySynthesis.cpp so ZYZ and KAK synthesis share phase-correction emission.
• Select a legal scalar phase anchor:
  • prefer the last scalar !quake.ref / !quake.wire target
  • extract the last element of a statically sized !quake.veq<N> when needed
  • retain the exact legacy r1/rz representation for unsized vector-only targets, where no scalar anchor is available.
• Retain KAK's modular helper-call graph. Its unpredicated quake.apply calls are later specialized transitively when an outer caller supplies controls.
• Update existing unitary-synthesis goldens to check the pre-lowering quake.phase form.

Tests

Add coverage for:

• controlled one-qubit synthesized helpers and phase lowering
  ` controlled KAK synthesis
• static vector targets requiring an extracted scalar anchor
• unsized vector-only targets requiring the legacy fallback

Update existing unitary-synthesis golden tests

[github-actions]

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