Rewrite project file drop zone.

Folder drops still skip KiCad backups/pretty/3dmodels; dashed upload chrome is unchanged.

tests/test_periscope_frontend_upload_rewrite.py

@@ -0,0 +1,19 @@
+"""Project file drop zone lives under periscope/src."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+SRC = ROOT / "periscope" / "src" / "frontend" / "src" / "components/upload/file-upload-zone.tsx"
+
+
+def test_upload_zone_is_src():
+    text = SRC.read_text(encoding="utf-8")
+    assert "Native Periscope overlay" not in text[:400]
+    assert "export function FileUploadZone" in text
+    assert "webkitGetAsEntry" in text
+    assert "webkitRelativePath" in text
+    assert "-backups" in text
+    assert "border-dashed" in text
+    assert "border-emerald-500/40" in text