P1 fix: Add class_exists() guard in PRC_Preset_Provider before
instantiating PR Core repository classes. If PR Core constant is
defined but classes fail to autoload, fall back to defaults instead
of crashing.
P2 fixes:
- Remove unused nonce from wp_localize_script (all endpoints public)
- Add cross-reference comments pinning SYRINGE_UNITS_PER_ML across
PRC_Math, calculator.js, and prcConfig.syringeUnits
QA verdict: qa-reviews/peptide-reconstitution-calculator/2026-04-17-9aa5309.md
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
babc2ae72a