refactor: simplify Langfuse integration with AI SDK 6 (#375)

- Remove manual token attribute setting (AI SDK 6 telemetry auto-reports)
- Use totalTokens directly instead of inputTokens + outputTokens calculation
- Fix sessionId bug in log-save/log-feedback (prevents wrong trace attachment)
- Hash IP addresses for privacy instead of storing raw IPs
- Fix isLangfuseEnabled() to check both keys for consistency

components/chat-panel.tsx

@@ -632,21 +632,15 @@ Continue from EXACTLY where you stopped.`,
 
             // DEBUG: Log finish reason to diagnose truncation
             console.log("[onFinish] finishReason:", metadata?.finishReason)
-            console.log("[onFinish] metadata:", metadata)
 
-            if (metadata) {
-                // Use Number.isFinite to guard against NaN (typeof NaN === 'number' is true)
-                const inputTokens = Number.isFinite(metadata.inputTokens)
-                    ? (metadata.inputTokens as number)
+            // AI SDK 6 provides totalTokens directly
+            const totalTokens =
+                metadata && Number.isFinite(metadata.totalTokens)
+                    ? (metadata.totalTokens as number)
                     : 0
-                const outputTokens = Number.isFinite(metadata.outputTokens)
-                    ? (metadata.outputTokens as number)
-                    : 0
-                const actualTokens = inputTokens + outputTokens
-                if (actualTokens > 0) {
-                    quotaManager.incrementTokenCount(actualTokens)
-                    quotaManager.incrementTPMCount(actualTokens)
-                }
+            if (totalTokens > 0) {
+                quotaManager.incrementTokenCount(totalTokens)
+                quotaManager.incrementTPMCount(totalTokens)
             }
         },
         sendAutomaticallyWhen: ({ messages }) => {