test: replace wall-clock loop deadlines with progress criteria

Three real-engine throughput loops (thumbnail pipeline, full-res fill
behind the proxy, playback window supply) failed on machine slowness:
their pass/fail was a wall-clock Instant deadline, so a loaded machine
broke them for speed, not for a broken pipeline. Each loop now counts
engine pumps — machine-speed independent — and asserts the condition
within a bounded number of pumps. The two single-frame worker channel
receives keep a generous 60 s recv_timeout (a one-shot bounded
operation, not a throughput loop).

oak-cli: the integration fixtures moved with the app crate during the
workspace restructure; point the fixture helpers at
../oak-app/tests instead of the (now empty) repo-root tests/.

crates/oak-cli/tests/cli.rs

@@ -42,17 +42,17 @@ fn bin() -> &'static str {
 
 /// The fixture `.ove` file (relative to the workspace root).
 fn fixture_project() -> PathBuf {
+	// The fixtures live with the app crate (moved there in the workspace
+	// restructure); oak-cli sits one level below oak-app.
 	Path::new(env!("CARGO_MANIFEST_DIR"))
-		.join("../..")
-		.join("tests")
+		.join("../oak-app/tests")
 		.join("project_with_footage.ove")
 }
 
 /// The real media fixture.
 fn fixture_media() -> PathBuf {
 	Path::new(env!("CARGO_MANIFEST_DIR"))
-		.join("../..")
-		.join("tests")
+		.join("../oak-app/tests")
 		.join("demo.mp4")
 }
 
@@ -60,8 +60,7 @@ fn fixture_media() -> PathBuf {
 /// no audio — fast end-to-end transcode coverage.
 fn fixture_image() -> PathBuf {
 	Path::new(env!("CARGO_MANIFEST_DIR"))
-		.join("../..")
-		.join("tests")
+		.join("../oak-app/tests")
 		.join("img.png")
 }