chore: format the tree and clear ruff's findings

Applies ruff format, ruff check --fix and prettier, so CI can gate on all three.
The surviving unused imports were all re-exports in __init__.py, now covered by a
per-file ignore; the pdf.js viewer and the generated openapi types join the
vendored code that eslint and prettier already skip.

frontend/src/lib/components/ui/icon-picker/icon-picker.svelte

@@ -45,11 +45,7 @@
 		{/snippet}
 	</Popover.Trigger>
 	<Popover.Content class="w-64 p-3" align="start">
-		<Input
-			bind:value={search}
-			placeholder="Search icons..."
-			class="mb-3 h-8"
-		/>
+		<Input bind:value={search} placeholder="Search icons..." class="mb-3 h-8" />
 		<ScrollArea class="h-48">
 			<div class="grid grid-cols-6 gap-1">
 				{#each filteredIcons as [key, icon] (key)}
@@ -58,7 +54,10 @@
 						<Tooltip.Trigger>
 							<button
 								type="button"
-								class="flex size-8 items-center justify-center rounded-md hover:bg-accent {value === key ? 'bg-accent' : ''}"
+								class="flex size-8 items-center justify-center rounded-md hover:bg-accent {value ===
+								key
+									? 'bg-accent'
+									: ''}"
 								onclick={() => selectIcon(key)}
 							>
 								<IconComponent class="size-4" />