feat(render): add per-output DRM outcome diagnostics (#52)

Co-authored-by: Samuel Onoja <[email protected]>

docs/README.md

@@ -45,6 +45,7 @@ and [guides at that tag](https://github.com/ferese-wm/ferese/tree/v0.1.0-beta/do
 - [Publishing activities](development/activities.md): IPC schema, ownership, limits and templates.
 - [Animation model](animation-model.md): geometry, spring motion, gestures and prediction.
 - [Desktop reconciliation](desktop-reconciliation.md): topology publication and presentation ownership.
+- [Rendering diagnostics](rendering-performance.md): outcome counters, capture cost and repeatable hardware baselines.
 - [Output management tests](output-management-testing.md): profiles, hotplug and DRM failures.
 - [Nested resize checks](nested-resize-testing.md).
 - [Client soak testing](native-soak-testing.md).