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>

peptide-reconstitution-calculator.php

@@ -0,0 +1,45 @@
+<?php
+/**
+ * Plugin Name: Peptide Reconstitution Calculator
+ * Plugin URI:  https://peptiderepo.com/tools/reconstitution-calculator
+ * Description: Interactive reconstitution calculator with peptide-specific presets from Peptide Repo Core. Computes concentration, injection volume, syringe units, and doses per vial.
+ * Version:     1.0.0
+ * Author:      peptiderepo
+ * Author URI:  https://peptiderepo.com
+ * License:     GPL-2.0-or-later
+ * Text Domain: peptide-reconstitution-calculator
+ * Requires PHP: 8.1
+ *
+ * @see ARCHITECTURE.md — Full data flow and file tree.
+ * @see CONVENTIONS.md  — Naming patterns and extension guides.
+ *
+ * Depends on: Peptide Repo Core (optional — provides peptide-specific presets).
+ * Without PR Core, the calculator still works with manual entry and built-in defaults.
+ */
+
+declare(strict_types=1);
+
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
+/* ── Constants ────────────────────────────────────────────────────────── */
+
+define( 'PRC_VERSION', '1.0.0' );
+define( 'PRC_PLUGIN_FILE', __FILE__ );
+define( 'PRC_PLUGIN_DIR', plugin_dir_path( __FILE__ ) );
+define( 'PRC_PLUGIN_URL', plugin_dir_url( __FILE__ ) );
+
+/* ── Autoloader ───────────────────────────────────────────────────────── */
+
+require_once PRC_PLUGIN_DIR . 'includes/class-prc-autoloader.php';
+PRC_Autoloader::register();
+
+/* ── Activation / Deactivation ────────────────────────────────────────── */
+
+register_activation_hook( __FILE__, [ 'PRC_Activator', 'activate' ] );
+register_deactivation_hook( __FILE__, [ 'PRC_Deactivator', 'deactivate' ] );
+
+/* ── Boot ─────────────────────────────────────────────────────────────── */
+
+add_action( 'plugins_loaded', [ 'PRC_Calculator', 'boot' ] );