ci(verify): run the wall-clock crash and realtime playback tests first and alone

.config/nextest.toml

@@ -11,6 +11,17 @@ slow-timeout = { period = "60s" }
 filter = 'binary_id(cap-rendering) and test(/^decoder::model::/)'
 threads-required = 3
 
+# Wall-clock tests run first and alone. crash_safety hands frames to a
+# real-time VideoToolbox session on a 30 fps schedule, and realtime_loop
+# counts the frames playback presents against the clock. Sharing the runner
+# with the seek storms, chaos and export tests starves them. On macOS,
+# crash/equality lost 3 to 7 frames in 6 shared runs and passed in all 6
+# solo reruns; realtime30 presented 65% of its frames shared and passed solo.
+[[profile.default.overrides]]
+filter = '(binary_id(cap-verify::crash) and test(=crash_safety)) or (binary_id(cap-verify::playback) and test(=realtime_loop))'
+threads-required = "num-test-threads"
+priority = 100
+
 [profile.ci]
 # No retries: a flaky case is a bug. run.sh reruns failures once afterwards
 # only to label them flaky in the job summary; the job still fails.
@@ -31,6 +42,12 @@ store-failure-output = true
 filter = 'binary_id(cap-rendering) and test(/^decoder::model::/)'
 threads-required = 3
 
+# Wall-clock tests run first and alone, as in the default profile.
+[[profile.ci.overrides]]
+filter = '(binary_id(cap-verify::crash) and test(=crash_safety)) or (binary_id(cap-verify::playback) and test(=realtime_loop))'
+threads-required = "num-test-threads"
+priority = 100
+
 
 # The FULL-tier seek storms (3000 seeks per decoder) are the slowest tests:
 # on the macos-15 runner one storm fixture takes 240 to 570 s per decoder,