fix(normalizer): keep Task 5 scoped — drop year-only matcher (belongs to Task 8)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tools/import-normalizer/dates.py

@@ -116,17 +116,8 @@ def _match_numeric(s):
         return None
 
 
-_YEAR_ONLY_RE = re.compile(r"\d{4}")
-
-
-def _match_year_only(s):
-    if _YEAR_ONLY_RE.fullmatch(s):
-        return datetime.date(int(s), 1, 1).isoformat(), Precision.YEAR
-    return None
-
-
 # Matchers are tried in order. Later tasks append to this list.
-_MATCHERS = [_match_iso, _match_numeric, _match_year_only]
+_MATCHERS = [_match_iso, _match_numeric]
 
 
 def parse_date(raw: str, date_overrides: dict | None = None) -> ParsedDate: