fix(FN-1014): add fallback reset time for Claude session window when API omits resets_at

- When the Claude usage API omits resets_at for the 5-hour session window, fall back to using the full window duration as resetMs
- This enables pace calculation and reset text display even without an explicit reset timestamp
- Update existing test to verify fallback behavior (resetMs = 5h, resetText = 'resets in 5h')
- Add new test for pace calculation with fallback reset time

packages/dashboard/src/usage.ts

@@ -842,6 +842,13 @@ async function fetchClaudeUsage(): Promise<ProviderUsage> {
         const msLeft = new Date(resetAtValue).getTime() - Date.now();
         resetMs = msLeft > 0 ? msLeft : 0;
         resetText = msLeft > 0 ? `resets in ${formatDuration(msLeft)}` : "resetting now";
+      } else if (windowDurationMs === FIVE_HOURS_MS) {
+        // Fallback for session window: when the API doesn't provide reset time,
+        // use the full window duration as a best-effort estimate. This enables
+        // pace calculation and reset text for the session (5h) window even when
+        // the API omits resets_at / reset_at / resetAt fields.
+        resetMs = windowDurationMs;
+        resetText = "resets in 5h";
       }
 
       return {