feat(factory): add local flashing toolkit and secure OTA defaults

tools/esptool-factory/factory_gui/time_utils.py

@@ -0,0 +1,35 @@
+from __future__ import annotations
+
+from datetime import datetime, timezone
+from typing import Optional
+
+
+def _now_iso() -> str:
+    return datetime.now(timezone.utc).isoformat()
+
+
+def _parse_iso_time(value: str) -> Optional[datetime]:
+    if not isinstance(value, str) or not value.strip():
+        return None
+    text = value.strip()
+    if text.endswith("Z"):
+        text = text[:-1] + "+00:00"
+    try:
+        parsed = datetime.fromisoformat(text)
+    except ValueError:
+        return None
+    if parsed.tzinfo is None:
+        parsed = parsed.replace(tzinfo=timezone.utc)
+    return parsed
+
+
+def _coerce_epoch_seconds(value: object) -> Optional[int]:
+    if isinstance(value, bool):
+        return None
+    if isinstance(value, (int, float)):
+        return int(value)
+    if isinstance(value, str):
+        stripped = value.strip()
+        if stripped.isdigit():
+            return int(stripped)
+    return None