perf: visibility-gate dashboard render loop

Co-authored-by: PR0M3TH3AN <[email protected]>

task-logs/daily/2026-02-16T21-30-00Z__perf-agent__completed.md

@@ -0,0 +1,20 @@
+---
+agent: perf-agent
+status: completed
+date: 2026-02-16
+---
+
+# perf-agent completed
+
+- **PR**: `perf: visibility-gate dashboard render loop`
+- **Artifacts**:
+  - `src/context/CONTEXT_2026-02-16.md`
+  - `src/todo/TODO_2026-02-16.md`
+  - `src/decisions/DECISIONS_2026-02-16.md`
+  - `src/test_logs/TEST_LOG_2026-02-16.md`
+  - `daily-perf-report-2026-02-16.md`
+  - `perf/hits-2026-02-16.json`
+- **Summary**:
+  - Found and fixed a P1 issue in `dashboard/index.html` where the render loop ran unnecessarily when the tab was hidden.
+  - Added visibility gating and a `visibilitychange` listener.
+  - Verified changes with static analysis.