refactor(document): extract DocumentTopBarActions from DocumentTopBar

Third Phase 5 split. The desktop action buttons — transcribe,
transcribe-stop, edit link, download link — become their own component
with a focused props interface (documentId, canWrite, isPdf,
transcribeMode bindable, filePath, originalFilename, fileUrl).

TDD: 8 tests covering empty render, transcribe button gating
(canWrite × isPdf × transcribeMode), stop-transcribe rendering, edit
link with documentId href, download link with filePath gating, all
hidden when in transcribe mode. After the test was red the component
was created.

DocumentTopBar dropped from 303 lines to 166. The orchestrator now
just composes BackButton, DocumentTopBarTitle, PersonChipRow,
OverflowPillButton, the details toggle, DocumentTopBarActions,
DocumentMobileMenu, and DocumentMetadataDrawer — each visual region
named in one or two words.

Refs #496.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/lib/document/DocumentTopBarActions.svelte

@@ -0,0 +1,103 @@
+<script lang="ts">
+import { m } from '$lib/paraglide/messages.js';
+
+type Props = {
+	documentId: string;
+	canWrite: boolean;
+	isPdf: boolean;
+	transcribeMode: boolean;
+	filePath?: string | null;
+	originalFilename?: string | null;
+	fileUrl: string;
+};
+
+let {
+	documentId,
+	canWrite,
+	isPdf,
+	transcribeMode = $bindable(),
+	filePath = null,
+	originalFilename = null,
+	fileUrl
+}: Props = $props();
+</script>
+
+{#if canWrite && isPdf && !transcribeMode}
+	<button
+		onclick={() => (transcribeMode = true)}
+		aria-label={m.transcription_mode_label()}
+		aria-pressed={false}
+		class="hidden items-center gap-1.5 rounded border border-primary px-3 py-1.5 font-sans text-[16px] font-medium text-ink transition hover:bg-primary hover:text-primary-fg focus-visible:ring-2 focus-visible:ring-primary md:flex"
+	>
+		<svg
+			class="h-5 w-5 shrink-0"
+			fill="none"
+			viewBox="0 0 24 24"
+			stroke="currentColor"
+			stroke-width="1.5"
+		>
+			<path
+				stroke-linecap="round"
+				stroke-linejoin="round"
+				d="M19.5 14.25v-2.625a3.375 3.375 0 00-3.375-3.375h-1.5A1.125 1.125 0 0113.5 7.125v-1.5a3.375 3.375 0 00-3.375-3.375H8.25m0 12.75h7.5m-7.5 3H12M10.5 2.25H5.625c-.621 0-1.125.504-1.125 1.125v17.25c0 .621.504 1.125 1.125 1.125h12.75c.621 0 1.125-.504 1.125-1.125V11.25a9 9 0 00-9-9z"
+			/>
+		</svg>
+		{m.transcription_mode_label()}
+	</button>
+{/if}
+
+{#if transcribeMode}
+	<button
+		onclick={() => (transcribeMode = false)}
+		aria-label={m.transcription_mode_stop()}
+		aria-pressed={true}
+		class="flex items-center gap-1.5 rounded bg-primary px-3 py-1.5 font-sans text-[16px] font-medium text-primary-fg transition focus-visible:ring-2 focus-visible:ring-primary"
+	>
+		<svg
+			class="h-5 w-5 shrink-0"
+			fill="none"
+			viewBox="0 0 24 24"
+			stroke="currentColor"
+			stroke-width="1.5"
+		>
+			<path
+				stroke-linecap="round"
+				stroke-linejoin="round"
+				d="M19.5 14.25v-2.625a3.375 3.375 0 00-3.375-3.375h-1.5A1.125 1.125 0 0113.5 7.125v-1.5a3.375 3.375 0 00-3.375-3.375H8.25m0 12.75h7.5m-7.5 3H12M10.5 2.25H5.625c-.621 0-1.125.504-1.125 1.125v17.25c0 .621.504 1.125 1.125 1.125h12.75c.621 0 1.125-.504 1.125-1.125V11.25a9 9 0 00-9-9z"
+			/>
+		</svg>
+		{m.transcription_mode_stop()}
+	</button>
+{/if}
+
+{#if canWrite && !transcribeMode}
+	<a
+		href="/documents/{documentId}/edit"
+		aria-label={m.btn_edit()}
+		class="flex items-center gap-1.5 rounded border border-primary bg-transparent px-3 py-1.5 text-[16px] font-medium text-ink transition hover:bg-primary hover:text-primary-fg focus-visible:ring-2 focus-visible:ring-primary"
+	>
+		<img
+			src="/degruyter-icons/Simple/Medium-24px/SVG/Action/Edit-Content-MD.svg"
+			alt=""
+			aria-hidden="true"
+			class="h-5 w-5"
+		/>
+		<span class="hidden sm:inline">{m.btn_edit()}</span>
+	</a>
+{/if}
+
+{#if filePath && !transcribeMode}
+	<a
+		href={fileUrl}
+		download={originalFilename}
+		class="hidden rounded border border-transparent bg-muted p-1.5 text-ink transition hover:bg-accent focus-visible:ring-2 focus-visible:ring-primary md:block"
+		title={m.doc_download_title()}
+	>
+		<img
+			src="/degruyter-icons/Simple/Medium-24px/SVG/Action/Download-MD.svg"
+			alt=""
+			aria-hidden="true"
+			class="h-5 w-5 shrink-0"
+		/>
+	</a>
+{/if}