fix(reader): PDF contents drawer rendered nothing — duplicate x-for keys

Diagnosed in a real browser (playwright/chromium against the running
app + Head First SQL): the engine's book.toc held all 18 entries with
correct labels/hrefs and the tab counter even showed 380, yet zero
links rendered while the console flooded with 'Alpine Warning:
Duplicate key on x-for'.

Root cause: the drawer keyed TOC rows by item.href. PDF outline
entries frequently share the same destination (e.g. the printed TOC
page is targeted by several bookmark entries), so flattened items
carried duplicate keys — and Alpine's x-for renders NOTHING for a
duplicated key, not even the unique ones. EPUB TOCs never collided
because their hrefs are unique file paths, which is why this only
surfaced on PDFs.

Key is now href + row index (the list is static once loaded, so
positional keys are safe). Verified end-to-end in the browser: 18
entries render and the drawer populates.

templates/reader.templ

@@ -533,7 +533,10 @@ templ ReaderTOCDrawer() {
 	</div>
 	<div class="reader-drawer-body">
 		<nav id="toc-list" class="space-y-1" x-show="tocTab === 'contents' || !isFixedLayout">
-			<template x-for="item in tocItems" :key="item.href">
+			<!-- Key must include the index: PDF outline entries can share the
+			     same destination href, and Alpine's x-for renders nothing on
+			     duplicate keys. -->
+			<template x-for="(item, idx) in tocItems" :key="item.href + '::' + idx">
 				<a
 					href="#"
 					@click.prevent="goToTOCItem(item)"

templates/reader_templ.go

@@ -357,7 +357,7 @@ func ReaderTOCDrawer() templ.Component {
 		if templ_7745c5c3_Err != nil {
 			return templ_7745c5c3_Err
 		}
-		templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 18, "<!-- Fixed-layout books get a Pages (thumbnails) tab; outline TOC may be\n\t     absent in manga-scan PDFs and CBZs. --><div class=\"reader-tabs\" x-show=\"isFixedLayout\"><button :class=\"tocTab === 'contents' ? 'active' : ''\" @click=\"tocTab = 'contents'\">Contents <span class=\"reader-tab-count\" x-text=\"tocItems.length\">0</span></button> <button :class=\"tocTab === 'pages' ? 'active' : ''\" @click=\"tocTab = 'pages'; initPageThumbs()\">Pages <span class=\"reader-tab-count\" x-text=\"pageThumbList.length || ''\">0</span></button></div><div class=\"reader-drawer-body\"><nav id=\"toc-list\" class=\"space-y-1\" x-show=\"tocTab === 'contents' || !isFixedLayout\"><template x-for=\"item in tocItems\" :key=\"item.href\"><a href=\"#\" @click.prevent=\"goToTOCItem(item)\" class=\"block py-1 px-2 rounded hover:bg-gray-700 text-sm\" :style=\"'padding-left: ' + ((item.depth || 0) * 1 + 0.5) + 'rem'\" x-text=\"item.label\"></a></template><template x-if=\"tocItems.length === 0\"><p class=\"text-sm py-2\" style=\"color: var(--text-secondary)\">No table of contents</p></template></nav><div id=\"page-thumb-grid\" class=\"reader-thumb-grid\" x-show=\"isFixedLayout && tocTab === 'pages'\"><template x-for=\"p in pageThumbList\" :key=\"p.index\"><button class=\"reader-thumb\" :class=\"p.index === currentPageIndex ? 'active' : ''\" @click=\"goToPage(p.index)\" :title=\"'Page ' + (p.index + 1)\"><div class=\"reader-thumb-img\" :data-page=\"p.index\"></div><span class=\"reader-thumb-num\" x-text=\"p.index + 1\">1</span></button></template><template x-if=\"pageThumbList.length === 0\"><p class=\"text-sm py-2\" style=\"color: var(--text-secondary)\">No pages</p></template></div></div>")
+		templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 18, "<!-- Fixed-layout books get a Pages (thumbnails) tab; outline TOC may be\n\t     absent in manga-scan PDFs and CBZs. --><div class=\"reader-tabs\" x-show=\"isFixedLayout\"><button :class=\"tocTab === 'contents' ? 'active' : ''\" @click=\"tocTab = 'contents'\">Contents <span class=\"reader-tab-count\" x-text=\"tocItems.length\">0</span></button> <button :class=\"tocTab === 'pages' ? 'active' : ''\" @click=\"tocTab = 'pages'; initPageThumbs()\">Pages <span class=\"reader-tab-count\" x-text=\"pageThumbList.length || ''\">0</span></button></div><div class=\"reader-drawer-body\"><nav id=\"toc-list\" class=\"space-y-1\" x-show=\"tocTab === 'contents' || !isFixedLayout\"><!-- Key must include the index: PDF outline entries can share the\n\t\t\t     same destination href, and Alpine's x-for renders nothing on\n\t\t\t     duplicate keys. --><template x-for=\"(item, idx) in tocItems\" :key=\"item.href + '::' + idx\"><a href=\"#\" @click.prevent=\"goToTOCItem(item)\" class=\"block py-1 px-2 rounded hover:bg-gray-700 text-sm\" :style=\"'padding-left: ' + ((item.depth || 0) * 1 + 0.5) + 'rem'\" x-text=\"item.label\"></a></template><template x-if=\"tocItems.length === 0\"><p class=\"text-sm py-2\" style=\"color: var(--text-secondary)\">No table of contents</p></template></nav><div id=\"page-thumb-grid\" class=\"reader-thumb-grid\" x-show=\"isFixedLayout && tocTab === 'pages'\"><template x-for=\"p in pageThumbList\" :key=\"p.index\"><button class=\"reader-thumb\" :class=\"p.index === currentPageIndex ? 'active' : ''\" @click=\"goToPage(p.index)\" :title=\"'Page ' + (p.index + 1)\"><div class=\"reader-thumb-img\" :data-page=\"p.index\"></div><span class=\"reader-thumb-num\" x-text=\"p.index + 1\">1</span></button></template><template x-if=\"pageThumbList.length === 0\"><p class=\"text-sm py-2\" style=\"color: var(--text-secondary)\">No pages</p></template></div></div>")
 		if templ_7745c5c3_Err != nil {
 			return templ_7745c5c3_Err
 		}