fix: clamp negative offset to 0 in getTimeline

Negative offset values passed through to Array.slice() use JS tail-indexing
semantics, returning commits from the wrong end of the array and producing
nonsensical pagination headers.

Author: piotrski

packages/agent-react-devtools/src/profiler.ts

@@ -324,7 +324,7 @@ export class Profiler {
     }));
 
     if (sort === 'duration') all.sort((a, b) => b.duration - a.duration);
-    const start = offset ?? 0;
+    const start = Math.max(0, offset ?? 0);
     return {
       entries: all.slice(start, start + limit),
       total: all.length,