feat: ship Peptide Reconstitution Calculator v1.0.0

Interactive reconstitution calculator with peptide-specific presets.

Core features:
- [prc_calculator] shortcode with instant client-side math
- Concentration (mg/mL), mcg/unit, injection volume, syringe units, doses/vial
- Live presets from PR Core dosing data (graceful fallback to 8 defaults)
- REST API (prc/v1): presets list/detail + server-side calculate
- Transient-cached presets with event-driven invalidation
- Dark mode + responsive design (320px+)
- Full teardown in uninstall.php

12 PHP files (max 241 lines), 1 JS file, 1 CSS file.
CI: PHP lint 8.1-8.3, PHPCS WordPress, 300-line check.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

phpcs.xml.dist

@@ -0,0 +1,18 @@
+<?xml version="1.0"?>
+<ruleset name="Peptide Reconstitution Calculator">
+	<description>WordPress coding standards for Peptide Reconstitution Calculator.</description>
+
+	<file>.</file>
+
+	<exclude-pattern>/vendor/*</exclude-pattern>
+	<exclude-pattern>/node_modules/*</exclude-pattern>
+	<exclude-pattern>/tests/*</exclude-pattern>
+	<exclude-pattern>/assets/*</exclude-pattern>
+
+	<arg name="extensions" value="php"/>
+	<arg name="severity" value="1"/>
+	<arg name="warning-severity" value="0"/>
+	<arg value="sp"/>
+
+	<rule ref="WordPress"/>
+</ruleset>