Stamp 2.60.0 incomplete PCB exam and owner project delete.

Partial layouts still use MODE=pcb. Missing copper is INSUFFICIENT or
skipped, never Euclidean stand-in tracks. Via≠Pad unchanged. DELETE
/api/projects/{id} is owner-only with a dashboard confirm dialog.

tests/test_periscope_leftover_package_requirements.py

@@ -17,7 +17,7 @@ DOCKERIGNORE = ROOT / ".dockerignore"
 def test_package_json_is_periscope_web():
     text = PKG.read_text(encoding="utf-8")
     assert '"name": "periscope-web"' in text
-    assert '"version": "2.59.0"' in text
+    assert '"version": "2.60.0"' in text
     assert "Native Periscope overlay" not in text[:400]
     assert LOCK.is_file()
     lock = LOCK.read_text(encoding="utf-8")