refactor(color): unify color sanitizing and picking behind shared components

- Add AKSRT\Core\Color::sanitize($value, $allow_alpha) as the single PHP
  color sanitizer; replace sanitize_hex_color calls and per-class regexes
  (FloatButtons, FieldSchema, ThemeSearch, icon cards, TicketStatusService)
- SchemaProvider / ControllerBase sanitize `color` fields as colors;
  alpha kept only when the schema sets showAlpha
- Split SchemaProvider OAuth validation and option matching into sibling
  traits to stay under the 1000-line limit
- Add AksColorPicker.vue + utils/color.js mirroring the PHP rules; AksField,
  FloatBtnCommonFields and TicketStatusPanel use it
- Widget background color input now uses wpColorPicker
- Remove dead AksCompositeField dimensions/spacing/background branches and
  the unused Gutenberg ColorPicker var
- Add color-unification contract test; update harness requires and tests

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/Admin/SchemaProviderOptionMatch.php

@@ -0,0 +1,75 @@
+<?php
+/**
+ * SchemaProvider 枚举字段取值归一化（大小写不敏感匹配 / 选项声明值回写）。
+ *
+ * @package AKSRT
+ */
+
+namespace AKSRT\Admin;
+
+defined('ABSPATH') || exit;
+
+trait SchemaProviderOptionMatch {
+
+	/**
+	 * 对大小写不敏感字段（case_insensitive），把值归一化为选项中的规范写法；
+	 * 匹配不到返回 null。
+	 *
+	 * @param mixed $value
+	 * @param array<int,mixed> $options
+	 */
+	private function normalize_case_insensitive_option($value, array $options): ?string {
+		if (!is_string($value) || $value === '') {
+			return null;
+		}
+		$lower = strtolower(trim($value));
+		foreach ($options as $opt) {
+			$opt_value = is_array($opt) ? ($opt['value'] ?? null) : $opt;
+			if (is_string($opt_value) && strtolower($opt_value) === $lower) {
+				return $opt_value;
+			}
+		}
+		return null;
+	}
+
+	/**
+	 * Resolve a submitted enum value to the value declared by its option.
+	 *
+	 * Payloads reach the sanitizer as strings (or numbers), so a strict match
+	 * against the schema would reject a valid choice whenever the option value
+	 * is not itself a string -- e.g. 积分兑换明细.level declares 1 / 2 while the
+	 * SPA submits them as numbers and sanitize_text_field() then turns them into
+	 * "1" / "2". Returning the declared value keeps the stored type aligned with
+	 * the schema, which the radio/select controls compare with === when they
+	 * re-render a saved setting.
+	 *
+	 * Returns null when nothing matches, so validation still reports the
+	 * invalid value instead of silently rewriting the operator's input.
+	 *
+	 * @param mixed $value
+	 * @param array<int,mixed> $options
+	 * @return mixed
+	 */
+	private function match_option_value($value, array $options) {
+		foreach ($options as $opt) {
+			$opt_value = is_array($opt) ? ($opt['value'] ?? null) : $opt;
+			if ($opt_value === $value) {
+				return $opt_value;
+			}
+		}
+		if (is_bool($value) || !is_scalar($value)) {
+			return null;
+		}
+		$needle = (string) $value;
+		foreach ($options as $opt) {
+			$opt_value = is_array($opt) ? ($opt['value'] ?? null) : $opt;
+			if (is_bool($opt_value) || !is_scalar($opt_value)) {
+				continue;
+			}
+			if ((string) $opt_value === $needle) {
+				return $opt_value;
+			}
+		}
+		return null;
+	}
+}