fix: rename deepseek model from deepseek-chat to deepseek-v4-pro

DeepSeek API deprecated deepseek-chat model. Returns error:
'the supported API model names are deepseek-v4-pro or deepseek-v4-flash'

Affected all 4 AI endpoints:
- risk-flags (90-day dashboard)
- triage-suggest
- rca-draft
- quality-check

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

app/api/incidents/ai/quality-check/route.ts

@@ -42,7 +42,7 @@ export async function POST(request: NextRequest) {
   let res: Awaited<ReturnType<typeof client.chat.completions.create>>
   try {
     res = await client.chat.completions.create({
-      model: 'deepseek-chat',
+      model: 'deepseek-v4-pro',
       max_tokens: 1024,
       tools: [{
         type: 'function',
@@ -99,7 +99,7 @@ Score 1–10 based on: specificity (location, time, persons involved), completen
   // audit write uses session.sub as a pseudo record-id (no incident_id at this stage)
   await withUser(session.sub, async tx => {
     await writeAuditLog(tx, 'incidents', session.sub, 'ai_quality_check', {
-      score: input.score, passes: input.passes, model: 'deepseek-chat',
+      score: input.score, passes: input.passes, model: 'deepseek-v4-pro',
     })
   })