[client] expose EGL stages in frame latency

Correlate received frames with the texture update actually consumed by
the renderer and retain damage until its token becomes renderable.

Split client latency into dispatch, import, queue, preparation, setup,
effects, desktop, composition, and swap stages in FRAME LATENCY.
Exclude diagnostic overlay work from composition and preserve client
wait time when producer timing is unavailable.

Publish joined samples through a bounded token queue, avoid sleeping
while producer timing is finalized, and correct Wayland photon units.

client/include/app.h

@@ -146,7 +146,9 @@ GraphHandle app_registerGraph(const char * name, RingBuffer buffer,
 void app_unregisterGraph(GraphHandle handle);
 void app_invalidateGraph(GraphHandle handle);
 void app_setGraphCompact(GraphHandle handle, bool compact);
-void app_setFrameImportTime(uint64_t time);
+/* Records nanosecond durations for the current frame's renderer import. The
+ * wait component overlaps producer work and is accounted for separately. */
+void app_setFrameImportTiming(uint64_t importTime, uint64_t importWaitTime);
 
 void app_overlayConfigRegister(const char * title,
     void (*callback)(void * udata, int * id), void * udata);