Fix GPT-5 API compatibility and add AIUsageLog migration

- Add AIUsageLog table migration for token tracking
- Fix GPT-5 temperature parameter (not supported, like o-series)
- Add usesNewTokenParam() and supportsTemperature() functions
- Add GPT-5+ category to model selection UI
- Update model sorting to show GPT-5+ first

GPT-5 and newer models use max_completion_tokens and don't support
custom temperature values, similar to reasoning models.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

prisma/migrations/20260203000000_add_ai_usage_log/migration.sql

@@ -0,0 +1,33 @@
+-- CreateTable
+CREATE TABLE "AIUsageLog" (
+    "id" TEXT NOT NULL,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "userId" TEXT,
+    "action" TEXT NOT NULL,
+    "entityType" TEXT,
+    "entityId" TEXT,
+    "model" TEXT NOT NULL,
+    "promptTokens" INTEGER NOT NULL,
+    "completionTokens" INTEGER NOT NULL,
+    "totalTokens" INTEGER NOT NULL,
+    "estimatedCostUsd" DECIMAL(10,6),
+    "batchSize" INTEGER,
+    "itemsProcessed" INTEGER,
+    "status" TEXT NOT NULL,
+    "errorMessage" TEXT,
+    "detailsJson" JSONB,
+
+    CONSTRAINT "AIUsageLog_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE INDEX "AIUsageLog_userId_idx" ON "AIUsageLog"("userId");
+
+-- CreateIndex
+CREATE INDEX "AIUsageLog_action_idx" ON "AIUsageLog"("action");
+
+-- CreateIndex
+CREATE INDEX "AIUsageLog_createdAt_idx" ON "AIUsageLog"("createdAt");
+
+-- CreateIndex
+CREATE INDEX "AIUsageLog_model_idx" ON "AIUsageLog"("model");