fix: switch AI endpoints from tool-calling to JSON output mode

DeepSeek v4-pro reasoning model rejects tool_choice parameter.
All 4 endpoints now use system prompts with JSON schema
instructions and parse content as JSON instead of tool_calls.

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

app/api/incidents/[id]/ai/triage-suggest/route.ts

@@ -52,48 +52,35 @@ export async function POST(
     res = await client.chat.completions.create({
       model: 'deepseek-v4-pro',
       max_tokens: 1024,
-      tools: [{
-        type: 'function',
-        function: {
-          name: 'suggest_triage',
-          description: 'Suggest severity rating and NADOPOD 2004 DOSH classification for a warehouse incident',
-          parameters: {
-            type: 'object',
-            properties: {
-              severity: { type: 'number', description: '1=minor, 2=low, 3=moderate, 4=serious, 5=critical/fatality' },
-              is_fatality: { type: 'boolean' },
-              is_serious_bodily_injury: { type: 'boolean', description: 'Fracture, amputation, blindness, serious burn, or similar' },
-              is_dangerous_occurrence: { type: 'boolean', description: 'Structural collapse, explosion, fire, scaffold collapse, etc.' },
-              is_occupational_disease: { type: 'boolean', description: 'Disease arising from workplace exposure' },
-              rationale: { type: 'string', description: 'One-sentence rationale citing NADOPOD 2004 where applicable' },
-            },
-            required: [
-              'severity', 'is_fatality', 'is_serious_bodily_injury',
-              'is_dangerous_occurrence', 'is_occupational_disease', 'rationale',
-            ],
-          },
+      messages: [
+        {
+          role: 'system',
+          content: `You are an HSE triage specialist for a Malaysian 3PL warehouse. Assess incidents under NADOPOD 2004. You must respond with valid JSON only — no markdown, no explanation outside the JSON object.
+
+Output exactly this JSON structure:
+{
+  "severity": <number 1-5, where 1=minor, 2=low, 3=moderate, 4=serious, 5=critical/fatality>,
+  "is_fatality": <boolean>,
+  "is_serious_bodily_injury": <boolean, true for fracture, amputation, blindness, serious burn, or similar>,
+  "is_dangerous_occurrence": <boolean, true for structural collapse, explosion, fire, scaffold collapse, etc.>,
+  "is_occupational_disease": <boolean, true for disease arising from workplace exposure>,
+  "rationale": "<one-sentence rationale citing NADOPOD 2004 where applicable>"
+}`,
         },
-      }],
-      tool_choice: { type: 'function', function: { name: 'suggest_triage' } },
-      messages: [{
-        role: 'user',
-        content: `You are an HSE triage specialist for a Malaysian 3PL warehouse. Assess this incident under NADOPOD 2004.
-
-Incident type: ${incident.incidentType}
-Description: ${incident.description}
-Injury involved: ${incident.injuryInvolved ? 'yes' : 'no'}
-Medical status: ${incident.medicalStatus ?? 'N/A'}
-Asset/equipment involved: ${incident.assetInvolved ? 'yes' : 'no'}
-
-Suggest severity (1–5) and tick the appropriate NADOPOD 2004 flags. Give a one-sentence rationale.`,
-      }],
+        {
+          role: 'user',
+          content: `Assess this incident under NADOPOD 2004. Respond with JSON only.\n\nIncident type: ${incident.incidentType}\nDescription: ${incident.description}\nInjury involved: ${incident.injuryInvolved ? 'yes' : 'no'}\nMedical status: ${incident.medicalStatus ?? 'N/A'}\nAsset/equipment involved: ${incident.assetInvolved ? 'yes' : 'no'}`,
+        },
+      ],
     })
   } catch {
     return NextResponse.json({ error: 'AI service unavailable' }, { status: 503 })
   }
 
-  const call = res.choices[0]?.message?.tool_calls?.[0]
-  if (!call || call.type !== 'function') return NextResponse.json({ error: 'AI suggestion failed' }, { status: 500 })
+  const raw = res.choices[0]?.message?.content
+  if (!raw) return NextResponse.json({ error: 'AI returned empty response' }, { status: 500 })
+
+  const json = raw.replace(/^```(?:json)?\s*/i, '').replace(/\s*```$/i, '').trim()
 
   let input: {
     severity?: unknown
@@ -103,7 +90,7 @@ Suggest severity (1–5) and tick the appropriate NADOPOD 2004 flags. Give a one
     is_occupational_disease?: unknown
     rationale?: unknown
   }
-  try { input = JSON.parse(call.function.arguments) }
+  try { input = JSON.parse(json) }
   catch { return NextResponse.json({ error: 'AI returned unexpected structure' }, { status: 500 }) }
 
   if (