harden domain architecture and add lazy Crossref+Unpaywall PDF enrichment with publications workspace refactor

app/services/domains/doi/normalize.py

@@ -0,0 +1,23 @@
+from __future__ import annotations
+
+import re
+from urllib.parse import unquote
+
+DOI_RE = re.compile(r"10\.\d{4,9}/[-._;()/:A-Z0-9]+", re.I)
+
+
+def normalize_doi(value: str | None) -> str | None:
+    if not value:
+        return None
+    match = DOI_RE.search(unquote(value))
+    if not match:
+        return None
+    return match.group(0).rstrip(" .;,)").lower()
+
+
+def first_doi_from_texts(*values: str | None) -> str | None:
+    for value in values:
+        doi = normalize_doi(value)
+        if doi:
+            return doi
+    return None