feat(phase9): History bulk select + bulk export

Slim leading checkbox on every row, tinted-row state when selected.
Bulk-action toolbar appears only when selection is non-empty: select
all (visible), clear, export selected (via exportTranscriptsToDir),
delete selected (single confirm). Esc clears selection. Cmd/Ctrl+A
selects all visible when focus is inside the list and not in a text
input. Stop-propagation on the checkbox keeps the click off the
row-expand toggle.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/pages/HistoryPage.svelte

@@ -44,6 +44,9 @@
   let showStarredOnly = $state(false);
   let activeTagFilter = $state(null); // null = all; string = tag value
   let expandedId = $state(null);
+  // Phase 9 bulk selection. Selection state is frontend-only and resets
+  // on page refresh by design.
+  let selected = $state(new Set());
   let playingId = $state(null);
   let audioEl = $state(null);
   let currentTime = $state(0);
@@ -348,6 +351,67 @@
     await saveTranscriptAsMarkdown(item);
   }
 
+  // Phase 9 bulk selection handlers.
+  function toggleSelected(id) {
+    const next = new Set(selected);
+    if (next.has(id)) next.delete(id);
+    else next.add(id);
+    selected = next;
+  }
+
+  function clearSelection() {
+    selected = new Set();
+  }
+
+  function selectAllVisible() {
+    selected = new Set(filtered.map((i) => i.id));
+  }
+
+  let selectedItems = $derived(history.filter((i) => selected.has(i.id)));
+
+  async function bulkExport() {
+    const items = selectedItems;
+    if (items.length === 0) return;
+    await exportTranscriptsToDir(items);
+    clearSelection();
+  }
+
+  async function bulkDelete() {
+    if (selected.size === 0) return;
+    const yes = confirm(
+      `Delete ${selected.size} transcript${selected.size === 1 ? "" : "s"}?`,
+    );
+    if (!yes) return;
+    for (const id of selected) deleteFromHistory(id);
+    clearSelection();
+  }
+
+  // Phase 9 keyboard shortcuts: Escape clears selection, Cmd/Ctrl+A
+  // selects all visible when the History list owns focus. The
+  // listEl?.contains check prevents hijacking Cmd+A inside text inputs
+  // outside the list (e.g. the search box, inline title input).
+  $effect(() => {
+    function onKey(e) {
+      if (e.key === "Escape" && selected.size > 0) {
+        clearSelection();
+        e.preventDefault();
+        return;
+      }
+      if ((e.key === "a" || e.key === "A") && (e.metaKey || e.ctrlKey)) {
+        const target = document.activeElement;
+        const inText =
+          target &&
+          (target.tagName === "INPUT" || target.tagName === "TEXTAREA");
+        if (!inText && listEl && listEl.contains(target)) {
+          selectAllVisible();
+          e.preventDefault();
+        }
+      }
+    }
+    window.addEventListener("keydown", onKey);
+    return () => window.removeEventListener("keydown", onKey);
+  });
+
   async function openEditor(item) {
     try {
       localStorage.setItem("kon_viewer_item", JSON.stringify(item));
@@ -454,6 +518,36 @@
     </div>
   {/if}
 
+  <!-- Phase 9 bulk-action toolbar. Surfaces only when selection is
+       non-empty, so the unselected default state is unchanged. -->
+  {#if selected.size > 0}
+    <div
+      class="mx-7 mb-3 flex items-center gap-3 px-4 py-2 rounded-lg border border-border-subtle bg-bg-elevated text-[12px]"
+      role="toolbar"
+      aria-label="Bulk actions for selected transcripts"
+    >
+      <span class="text-text-tertiary">{selected.size} selected</span>
+      <button
+        class="text-text hover:underline"
+        onclick={selectAllVisible}
+      >Select all</button>
+      <button
+        class="text-text-tertiary hover:text-text"
+        onclick={clearSelection}
+      >Clear</button>
+      <div class="ml-auto flex gap-4">
+        <button
+          class="text-text hover:underline"
+          onclick={bulkExport}
+        >Export selected</button>
+        <button
+          class="text-danger hover:underline"
+          onclick={bulkDelete}
+        >Delete selected</button>
+      </div>
+    </div>
+  {/if}
+
   <!-- History list -->
   <div class="flex-1 px-7 pb-4 min-h-0">
     <Card classes="h-full flex flex-col overflow-hidden">
@@ -469,7 +563,7 @@
               <div class="absolute left-0 right-0" style="top: {top}px; min-height: {height}px">
                 <!-- Compact row -->
                 <div
-                  class="flex items-center gap-3 px-4 py-3 border-b border-border-subtle bg-bg-card hover:bg-hover cursor-pointer"
+                  class="flex items-center gap-3 px-4 py-3 border-b border-border-subtle bg-bg-card hover:bg-hover cursor-pointer {selected.has(item.id) ? 'bg-accent/5' : ''}"
                   style="transition-duration: var(--duration-ui)"
                   onclick={() => toggleExpand(item.id)}
                   onkeydown={(e) => { if (e.key === "Enter" || e.key === " ") { e.preventDefault(); toggleExpand(item.id); } }}
@@ -477,6 +571,18 @@
                   tabindex="0"
                   aria-expanded={expandedId === item.id}
                 >
+                  <!-- Phase 9 bulk-select checkbox. Stays unobtrusive
+                       until checked or hovered; e.stopPropagation keeps
+                       the click off the row-expand toggle. -->
+                  <input
+                    type="checkbox"
+                    class="w-3.5 h-3.5 flex-shrink-0 accent-accent cursor-pointer opacity-50 hover:opacity-100 {selected.has(item.id) ? 'opacity-100' : ''}"
+                    aria-label={`Select transcript ${item.title || item.id}`}
+                    checked={selected.has(item.id)}
+                    onclick={(e) => { e.stopPropagation(); toggleSelected(item.id); }}
+                    onkeydown={(e) => { if (e.key === " " || e.key === "Enter") e.stopPropagation(); }}
+                  />
+
                   <!-- Play button (if audio exists) -->
                   {#if item.audioPath}
                     <button