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>

uninstall.php

@@ -0,0 +1,35 @@
+<?php
+/**
+ * Uninstall handler — cleans up all plugin data.
+ *
+ * What: Removes all options and transients created by this plugin.
+ * Who calls it: WordPress on plugin deletion.
+ * Dependencies: None (standalone, no autoloader).
+ *
+ * @see ARCHITECTURE.md — Teardown section.
+ */
+
+declare(strict_types=1);
+
+if ( ! defined( 'WP_UNINSTALL_PLUGIN' ) ) {
+	exit;
+}
+
+global $wpdb;
+
+// Delete all prc_ prefixed options.
+$wpdb->query(
+	$wpdb->prepare(
+		"DELETE FROM {$wpdb->options} WHERE option_name LIKE %s",
+		$wpdb->esc_like( 'prc_' ) . '%'
+	)
+);
+
+// Delete all prc_ prefixed transients.
+$wpdb->query(
+	$wpdb->prepare(
+		"DELETE FROM {$wpdb->options} WHERE option_name LIKE %s OR option_name LIKE %s",
+		$wpdb->esc_like( '_transient_prc_' ) . '%',
+		$wpdb->esc_like( '_transient_timeout_prc_' ) . '%'
+	)
+);