fix: the frontend type-checks again

`check frontend build` has been red on every head for a day, through four review
rounds that each came back clean — none of the reviewers type-check, and they
say so in their own coverage sections. Ten errors:

The dev badge's `label` and `color` were typed `string | undefined`, but the
workspace rows carry `string | null`, so all seven of its call sites failed.
`forkAccentStyle` took the same widening.

A Svelte transition is called with the node it animates, and `stripArrive` and
`stripLeave` were declared with no parameters at all.

And `DevWorkspaceSetting` still imported `Badge` after its badge moved into the
shared component.

`svelte-check` now reports 0 errors. Note that it only agrees with CI once
`src/lib/gen` has been regenerated — the gitignored client goes stale against
main and invents errors CI never sees.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

frontend/src/lib/components/DevWorkspaceBadge.svelte

@@ -16,10 +16,11 @@ before a colour could be picked.
 	import { twMerge } from 'tailwind-merge'
 
 	interface Props {
-		/** The workspace's `dev_workspace_label`; spelled the way `devBadgeText` spells it. */
-		label?: string | undefined
+		/** The workspace's `dev_workspace_label`; spelled the way `devBadgeText` spells it. Nullable
+		 *  because that is what the workspace rows carry. */
+		label?: string | null
 		/** The fork's own colour. Without one — or with an unparsable one — the badge falls back. */
-		color?: string | undefined
+		color?: string | null
 		/** The badge's colour when the fork has none of its own. */
 		fallbackColor?: BadgeColor
 		/** Extra classes for that same case, for a host that tuned the uncoloured badge. */

frontend/src/lib/components/DevWorkspaceSetting.svelte

@@ -2,7 +2,7 @@
 	import { workspaceStore, userWorkspaces, usersWorkspaceStore, superadmin } from '$lib/stores'
 	import { WorkspaceService, type ProtectionRuleset } from '$lib/gen'
 	import DevWorkspaceBadge from '$lib/components/DevWorkspaceBadge.svelte'
-	import { Badge, Button } from '$lib/components/common'
+	import { Button } from '$lib/components/common'
 	import Select from '$lib/components/select/Select.svelte'
 	import Toggle from '$lib/components/Toggle.svelte'
 	import { sendUserToast } from '$lib/toast'

frontend/src/lib/utils/forkColor.ts

@@ -120,7 +120,7 @@ function lightestAtContrast(
  * fork chip consumes (see WorkspaceScopeTrigger). Returns undefined for an
  * unparsable color, letting the chip fall back to the default accent.
  */
-export function forkAccentStyle(color: string | undefined): string | undefined {
+export function forkAccentStyle(color: string | null | undefined): string | undefined {
 	if (!color) return undefined
 	const parsed = hexToHsl(color)
 	if (!parsed) return undefined

frontend/src/routes/(root)/(logged)/sessions/+page.svelte

@@ -473,12 +473,12 @@
 	/** The arriving strip fades in over the expansion; the leaving one goes quickly, so the two
 	 *  are never both legible at once — they stand in different places, and a slow dissolve would
 	 *  read as two tab rows rather than one changing place. */
-	function stripArrive() {
+	function stripArrive(_node: Element) {
 		return reducedMotion.val
 			? { duration: 0 }
 			: { duration: 180, delay: 60, easing: cubicOut, css: (t: number) => `opacity: ${t}` }
 	}
-	function stripLeave() {
+	function stripLeave(_node: Element) {
 		return reducedMotion.val
 			? { duration: 0 }
 			: { duration: 80, easing: cubicOut, css: (t: number) => `opacity: ${t}` }