feat(models): add background task model override config and runtime wiring

src/context/compaction.ts

@@ -117,6 +117,7 @@ export async function compactHistory(opts: {
   const tier = orchestrator.getDelegationTier('compaction');
 
   const result = await orchestrator.delegate({
+    task: 'compaction',
     tier,
     systemPrompt: COMPACTION_SYSTEM_PROMPT,
     message: formattedConversation,
@@ -133,6 +134,7 @@ export async function compactHistory(opts: {
     try {
       const extractionTier = orchestrator.getDelegationTier('memory_extraction');
       const extraction = await orchestrator.delegate({
+        task: 'memory_extraction',
         tier: extractionTier,
         systemPrompt: MEMORY_EXTRACTION_PROMPT,
         message: `Extract persistent facts from this conversation:\n\n${formattedConversation}`,