fix(conversation): format thinking past an hour in hours

summarizeActivity only knew seconds and minutes, so an hour of
thinking read "Thought for 60m 00s". Durations of an hour or more now
read as hours and minutes ("1h 30m"); shorter ones are unchanged.

Author: pratikbuilds

src/lib/conversation-activity.test.ts

@@ -218,6 +218,12 @@ describe("summarizeActivity", () => {
     expect(summarizeActivity([thought(65_000)])).toBe("Thought for 1m 05s");
   });
 
+  test("formats durations past an hour in hours and minutes", () => {
+    expect(summarizeActivity([thought(3_599_000)])).toBe("Thought for 59m 59s");
+    expect(summarizeActivity([thought(3_600_000)])).toBe("Thought for 1h 00m");
+    expect(summarizeActivity([thought(5_400_000)])).toBe("Thought for 1h 30m");
+  });
+
   test("reads as work when nothing was thought", () => {
     expect(summarizeActivity([batch("b", [tool("b1"), tool("b2")])])).toBe(
       "Worked through 2 steps",

src/lib/conversation-activity.ts

@@ -81,7 +81,11 @@ export function groupActivity(
 function formatDuration(ms: number): string {
   const seconds = Math.max(1, Math.round(ms / 1000));
   if (seconds < 60) return `${seconds}s`;
-  return `${Math.floor(seconds / 60)}m ${String(seconds % 60).padStart(2, "0")}s`;
+  const minutes = Math.floor(seconds / 60);
+  if (minutes < 60) {
+    return `${minutes}m ${String(seconds % 60).padStart(2, "0")}s`;
+  }
+  return `${Math.floor(minutes / 60)}h ${String(minutes % 60).padStart(2, "0")}m`;
 }
 
 function countSteps(steps: readonly ActivityStep[]): number {