feat(dashboard): focus same-page Start Session input from NextStep CTA and checklist

The "Start a session" CTAs on the NextStepCard and SetupChecklist used to
Link-navigate, which left the user on the same page (the Start Session
input lives on the dashboard) without any visible response. Replace those
CTAs with a custom window-event dispatch (FOCUS_START_SESSION_EVENT) that
the StartSessionInput listens for: scroll the input into view, focus the
textarea, and pulse a ring for 900ms so the click feels intentional. The
NextStepCard also locally hides itself after firing so the user isn't
double-prompted while typing.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/components/dashboard/StartSessionInput.tsx

@@ -18,19 +18,38 @@ const SUGGESTIONS: { icon: LucideIcon; label: string }[] = [
 
 const ACCEPTED_FILE_TYPES = 'image/png,image/jpeg,image/gif,image/webp,.txt,.log,.csv,.pdf,.docx'
 
+export const FOCUS_START_SESSION_EVENT = 'rf:focus-start-session'
+
 export function StartSessionInput() {
   const [value, setValue] = useState('')
   const [showLogs, setShowLogs] = useState(false)
   const [logContent, setLogContent] = useState('')
   const [pendingUploads, setPendingUploads] = useState<PendingUpload[]>([])
   const [isDragOver, setIsDragOver] = useState(false)
+  const [nudge, setNudge] = useState(false)
   const navigate = useNavigate()
+  const wrapperRef = useRef<HTMLDivElement>(null)
   const textareaRef = useRef<HTMLTextAreaElement>(null)
   const fileInputRef = useRef<HTMLInputElement>(null)
   const dragCounterRef = useRef(0)
 
   useEffect(() => { textareaRef.current?.focus() }, [])
 
+  // External "focus me" trigger (e.g. NextStepCard "Start a session" CTA on
+  // the same page). Scrolls into view, focuses the textarea, and pulses a
+  // ring so the click feels intentional even when the input was already
+  // partially visible.
+  useEffect(() => {
+    const handler = () => {
+      wrapperRef.current?.scrollIntoView({ behavior: 'smooth', block: 'start' })
+      textareaRef.current?.focus({ preventScroll: true })
+      setNudge(true)
+      window.setTimeout(() => setNudge(false), 900)
+    }
+    window.addEventListener(FOCUS_START_SESSION_EVENT, handler)
+    return () => window.removeEventListener(FOCUS_START_SESSION_EVENT, handler)
+  }, [])
+
   // Auto-grow textarea
   useEffect(() => {
     const el = textareaRef.current
@@ -190,7 +209,8 @@ export function StartSessionInput() {
 
   return (
     <div
-      className="w-full"
+      ref={wrapperRef}
+      className="w-full scroll-mt-6"
       onDragOver={handleDragOver}
       onDragEnter={handleDragEnter}
       onDragLeave={handleDragLeave}
@@ -198,9 +218,11 @@ export function StartSessionInput() {
     >
       {/* Main input area */}
       <div className={cn(
-        'relative rounded-2xl border bg-card transition-all',
+        'relative rounded-2xl border bg-card transition-all duration-300',
         isDragOver ? 'border-primary/50 bg-primary/5' : 'border-border',
-        'focus-within:border-[rgba(96,165,250,0.25)] focus-within:ring-1 focus-within:ring-[rgba(96,165,250,0.1)]'
+        nudge
+          ? 'border-[rgba(96,165,250,0.6)] ring-2 ring-[rgba(96,165,250,0.35)] shadow-[0_0_0_6px_rgba(96,165,250,0.12)]'
+          : 'focus-within:border-[rgba(96,165,250,0.25)] focus-within:ring-1 focus-within:ring-[rgba(96,165,250,0.1)]'
       )}>
         {/* Drag overlay */}
         {isDragOver && (