feat(29-02): update detail pages and LinkToGlobalItem to use GearImage

Replace object-cover on item detail, global item detail, candidate
detail, global items index, and LinkToGlobalItem. Detail pages use
dominant color backgrounds. LinkToGlobalItem uses cover mode for
32px thumbnails.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/client/components/LinkToGlobalItem.tsx

@@ -1,5 +1,6 @@
 import { Link } from "@tanstack/react-router";
 import { useEffect, useState } from "react";
+import { GearImage } from "./GearImage";
 import {
 	useGlobalItem,
 	useGlobalItems,
@@ -177,11 +178,13 @@ export function LinkToGlobalItem({
 									className="w-full text-left px-3 py-2 hover:bg-gray-50 transition-colors flex items-center gap-2"
 								>
 									{item.imageUrl ? (
-										<img
-											src={item.imageUrl}
-											alt=""
-											className="w-8 h-8 rounded object-cover shrink-0"
-										/>
+										<div className="w-8 h-8 rounded overflow-hidden shrink-0">
+											<GearImage
+												src={item.imageUrl}
+												alt=""
+												cover
+											/>
+										</div>
 									) : (
 										<div className="w-8 h-8 rounded bg-gray-100 shrink-0" />
 									)}