fix: concatenate reasoning field in streaming response consolidation (#5578)

consolidateTextFields() only concatenated content and function_call
from streaming deltas, but not reasoning. This meant reasoning tokens
from providers like Gemini with thinking/reasoning would get
last-chunk-wins behavior instead of proper concatenation.

Adds reasoning field handling alongside content in the delta
consolidation logic.

Author: ink-the-squid

worker/src/lib/dbLogger/streamParsers/responseParserHelpers.ts

@@ -54,6 +54,10 @@ export function consolidateTextFields(responseBody: any[]): any {
                   content: c.delta.content
                     ? c.delta.content + (cur.choices[i].delta.content ?? "")
                     : cur.choices[i].delta.content,
+                  reasoning: c.delta.reasoning
+                    ? c.delta.reasoning +
+                      (cur.choices[i].delta.reasoning ?? "")
+                    : cur.choices[i].delta.reasoning,
                   function_call: c.delta.function_call
                     ? recursivelyConsolidate(
                         c.delta.function_call,