fix(deploy-to-hub): point Open in Hub link at the project slug, not the workspace

hubSlug was derived from $workspaceStore, so the Open in Hub link and badge
used the workspace id instead of the published project slug — navigating to
the wrong (or nonexistent) Hub project. Derive hubSlug from the actual
project slug (effectiveSlug, falling back to sanitizeSlug(hubName)).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/lib/components/workspaceSettings/DeployToHub.svelte

@@ -186,8 +186,6 @@
 	)
 
 	const EMPTY_SCHEMA = { type: 'object', properties: {}, required: [] }
-	let hubSlug = $derived($workspaceStore ?? '')
-	let hubUrl = $derived(`https://hub.windmill.dev/projects/${hubSlug}`)
 
 	let hubVersion = $state<number>(0)
 	let deploymentStatus = $state<
@@ -225,6 +223,9 @@
 
 	let effectiveSlug = $state('')
 
+	let hubSlug = $derived(effectiveSlug || sanitizeSlug(hubName))
+	let hubUrl = $derived(`https://hub.windmill.dev/projects/${hubSlug}`)
+
 	const delay = (ms: number) => new Promise((r) => setTimeout(r, ms))
 
 	function patchItem(key: string, patch: Partial<DeployItem>) {