feat(advisor): topic threads, per-question delete/copy, fullscreen

Adds case management to the Compliance Advisor widget.

- topic threads: cases group into threads; the left menu shows each
  thread's first question as the Thema with expandable follow-ups.
  Send = follow-up to the active thread (carries the thread's prior Q&A
  as history for contextual answers); "+" starts a new topic.
- delete: a trash action per question (menu + stacked view).
- copy: single Q&A (question + answer + evidence + footnotes) or a whole
  thread, as Markdown to the clipboard (pure formatters in copy.ts).
- fullscreen: compact -> panel -> fullscreen view.
- route.ts consumes an optional bounded `history` so follow-ups are
  contextual for both the widget and the workspace consumer.

Tests: copy formatter unit tests + Playwright specs (threads/new-topic,
delete, fullscreen, copy affordance). No deploy.

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

admin-compliance/app/api/sdk/compliance-advisor/chat/route.ts

@@ -75,12 +75,28 @@ function answerSystem(
   return s
 }
 
+// Prior thread turns for contextual follow-ups. Validated + bounded (last 8 turns ~ 4 Q&A).
+function parseHistory(raw: unknown): ChatMessage[] {
+  if (!Array.isArray(raw)) return []
+  const turns: ChatMessage[] = []
+  for (const t of raw) {
+    if (!t || typeof t !== 'object') continue
+    const role = (t as { role?: unknown }).role
+    const content = (t as { content?: unknown }).content
+    if ((role === 'user' || role === 'assistant') && typeof content === 'string' && content.trim()) {
+      turns.push({ role, content })
+    }
+  }
+  return turns.slice(-8)
+}
+
 export async function POST(request: NextRequest) {
   try {
     const body = await request.json()
     const question = String(body.question ?? body.message ?? '').trim()
     const context: string | null = body.context ?? null
     const audience = typeof body.audience === 'string' ? body.audience.trim() : ''
+    const history = parseHistory(body.history)
     const country = (['DE', 'AT', 'CH', 'EU'] as const).includes(body.country)
       ? (body.country as Country)
       : undefined
@@ -98,6 +114,7 @@ export async function POST(request: NextRequest) {
       const legacySoul = await readSoulFile('compliance-advisor')
       const legacyStream = await streamAdvisorAnswer([
         { role: 'system', content: answerSystem(legacySoul, country, numberedEvidenceForPrompt(legacyEvidence), false, audience) },
+        ...history,
         { role: 'user', content: question },
       ])
       if (!legacyStream) {
@@ -141,6 +158,7 @@ export async function POST(request: NextRequest) {
     const soul = await readSoulFile('compliance-advisor')
     const messages: ChatMessage[] = [
       { role: 'system', content: answerSystem(soul, country, numberedEvidenceForPrompt(evidence), true, audience) },
+      ...history,
       { role: 'user', content: question },
     ]
     const answer = await completeAdvisorAnswer(messages)