quality improvements

API key prompt is now "echo on" - echo off was useless given the context
sample name gets trimmed so only STD-ID is preserved in the filename
filename now contains technique (PLD) and ends in .nxs
all should be right in the world - and nffa-di data research policy
  compliant, spec.lly sect. 3.1.7-3.1.9

src/main.py

@@ -871,7 +871,7 @@ def build_nexus_file(pld_fabrication, output_path="output/nffa-di_unnamed.h5"):
 
 if __name__ == "__main__":
     load_dotenv()
-    api_key = os.getenv("api_key") or getpass("Paste API key here: ")
+    api_key = os.getenv("api_key") or getpass("Paste API key here: ", echo_char="*")
     elabid = (
         os.getenv("elabid")
         or input("Enter elabid of your starting sample [default = 1111]: ")
@@ -880,8 +880,12 @@ if __name__ == "__main__":
     handler = APIHandler(api_key)
     data = handler.get_entry_from_elabid(elabid)
     sample = Entrypoint(data)
-    sample_name = sample.name.strip().replace(" ", "_")
+    sample_name = sample.name.strip().replace(
+        " ", "-"
+    )  # returns error if no "title" or title is not str
     operative_unit = os.getenv("operative_unit") or None
+    if operative_unit:
+        operative_unit = operative_unit.strip().replace(" ", "-")
     if sample.proposal:
         sample_proposal = call_proposal_from_elabid(sample.proposal)
     else:
@@ -894,12 +898,12 @@ if __name__ == "__main__":
         "nffa-di_"
         + (f"{sample_proposal}_" if sample_proposal else "")
         + (f"{operative_unit}_" if operative_unit else "")
-        + "_"
+        + "PLD_"
-        + sample_name
+        + sample_name[:9]
     )
 
     result = make_nexus_schema_dictionary(substrate_object, layers)
     with open(f"output/{fn_base}.json", "w") as f:
         json.dump(result, f, indent=3)
 
-    build_nexus_file(result, output_path=f"output/{fn_base}.h5")
+    build_nexus_file(result, output_path=f"output/{fn_base}.nxs")