feat: live task token usage and stats-tab fixes

Capture per-session token usage from pi-coding-agent's getSessionStats()
after each promptWithFallback in the executor and merger paths, so
task.tokenUsage populates live during runs and reflects final totals on
done tasks. Previously the executor never read session usage and only
the heartbeat path bumped agent token totals, leaving task.tokenUsage
undefined even after completion.

Stats panel and done-card timing also now reflect live state: the modal
overlays the SSE-updated task prop on top of the one-shot fullDetail
snapshot, in-progress workflow steps contribute live elapsed to the
Workflow runtime metric, and the done card uses Timed duration (matching
the stats tab) with workflow runtime as fallback. Time indicator labels
coarsened to <1m / Nm / Nh / Nd.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/dashboard/app/utils/taskTiming.ts

@@ -0,0 +1,49 @@
+import type { TaskLogEntry } from "@fusion/core";
+
+export interface TimingEvent {
+  timestamp: string;
+  durationMs?: number;
+  summary: string;
+}
+
+function summarizeTimingLabel(entry: TaskLogEntry): string {
+  const timingText = entry.action || entry.outcome || "";
+  const stripped = timingText
+    .replace(/^\[timing\]\s*/i, "")
+    .replace(/^\[[^\]]+\]\s*/i, "")
+    .replace(/\s+in\s+\d+(?:\.\d+)?ms\b/i, "")
+    .replace(/\s+after\s+\d+(?:\.\d+)?ms\b/i, "")
+    .trim();
+  return stripped || "Timing event";
+}
+
+export function extractTimingEvents(logEntries: TaskLogEntry[]): TimingEvent[] {
+  return logEntries
+    .filter((entry) => {
+      const actionText = typeof entry.action === "string" ? entry.action : "";
+      const outcomeText = typeof entry.outcome === "string" ? entry.outcome : "";
+      return actionText.includes("[timing]") || outcomeText.includes("[timing]");
+    })
+    .map((entry) => {
+      const haystack = `${entry.action ?? ""}\n${entry.outcome ?? ""}`;
+      const durationMatch = haystack.match(/(\d+(?:\.\d+)?)ms\b/i);
+      const durationMs = durationMatch ? Number(durationMatch[1]) : undefined;
+      return {
+        timestamp: entry.timestamp,
+        durationMs: Number.isFinite(durationMs) ? durationMs : undefined,
+        summary: summarizeTimingLabel(entry),
+      };
+    });
+}
+
+export function getTimedDurationMs(logEntries: TaskLogEntry[] | undefined): number | null {
+  if (!logEntries || logEntries.length === 0) return null;
+  let total = 0;
+  let counted = 0;
+  for (const event of extractTimingEvents(logEntries)) {
+    if (typeof event.durationMs !== "number") continue;
+    total += event.durationMs;
+    counted += 1;
+  }
+  return counted > 0 ? total : null;
+}