fix: bib.sync — normalize timestamps to Zotero format (no T, no Z)

Zotero expects 'YYYY-MM-DD HH:MM:SS' for date fields, not ISO 8601
with T separator and Z suffix. Added _normalize_zotero_date() and
applied it to accessDate, dateEnacted, and date fields in _set_field().
Also fixed _now_iso() for dateAdded/dateModified on item creation.

src/bib/sync.py

@@ -94,7 +94,8 @@ def _is_valid_zotero_key(key: str) -> bool:
 
 
 def _now_iso() -> str:
-    return datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ")
+    """Zotero internal timestamp: ``YYYY-MM-DD HH:MM:SS`` (no T, no Z)."""
+    return datetime.now(timezone.utc).strftime("%Y-%m-%d %H:%M:%S")
 
 
 def _ensure_value(con: sqlite3.Connection, value: str) -> int:
@@ -118,6 +119,11 @@ def _ensure_tag(con: sqlite3.Connection, name: str) -> int:
     return cur.lastrowid
 
 
+def _normalize_zotero_date(value: str) -> str:
+    """Convert ISO 8601 timestamps to Zotero's format (no T, no Z)."""
+    return value.replace("T", " ").rstrip("Z")
+
+
 def _set_field(
     con: sqlite3.Connection,
     item_id: int,
@@ -130,6 +136,9 @@ def _set_field(
     field_id = _FIELD_IDS.get(field_name)
     if field_id is None:
         return
+    # Normalize date fields to Zotero's expected format
+    if field_name in ("accessDate", "dateEnacted", "date"):
+        value = _normalize_zotero_date(value)
     value_id = _ensure_value(con, value)
     con.execute(
         "INSERT OR REPLACE INTO itemData (itemID, fieldID, valueID) VALUES (?, ?, ?)",

tests/bib/test_sync.py

@@ -106,9 +106,9 @@ class TestZoteroKey:
 class TestNowIso:
     def test_format(self) -> None:
         result = _now_iso()
-        assert len(result) == 20  # "YYYY-MM-DDTHH:MM:SSZ"
+        assert len(result) == 19  # "YYYY-MM-DD HH:MM:SS"
-        assert "T" in result
+        assert " " in result
-        assert result.endswith("Z")
+        assert not result.endswith("Z")
 
 
 # ── _ensure_value ───────────────────────────────────────────────────