Expand L2 test vectors with seasons and decades

Adds 10 new rows to level2.tsv covering extended season codes and
the three-digit decade notation:

- Extended seasons: 2020-25, 2020-30, 2020-37, 2020-40, 2020-41
  (one from each grouping in edtf.js's season min/max tables:
  hemispheric variant, quadrimester, and half-year).
- Decades: 199, 202, -005 plus the three qualifier variants
  199?, 199~, 199%.

Consecutive ranges ({start..end}) are deliberately excluded from
the generated vector set because edtf.js and this port disagree on
the list max bound (edtf.js returns start.max while we return
end.max, which we consider the correct interpretation of the
range). The round-trip behaviour is still exercised by targeted
unit tests in L2ParserTest.

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

Author: jeffreyameyer

scripts/generate-vectors.mjs

@@ -48,6 +48,10 @@ const LEVEL2 = [
   '[2020, 2021]', '[2020, 2021, 2023]', '[..2020]', '[2020..]',
   // Lists (curly braces)
   '{2020, 2021}', '{2020}',
+  // Extended seasons (L2S codes 25-41)
+  '2020-25', '2020-30', '2020-37', '2020-40', '2020-41',
+  // Decades (standalone 3-digit)
+  '199', '202', '-005', '199?', '199~', '199%',
 ];
 
 const LEVEL1 = [

src/test/resources/vectors/level2.tsv

@@ -10,3 +10,14 @@ input	type	level	min	max	edtf
 [2020..]	Set	2	1577836800000	Infinity	[2020..]
 {2020, 2021}	List	2	1577836800000	1640995199999	{2020,2021}
 {2020}	List	2	1577836800000	1609459199999	{2020}
+2020-25	Season	2	1577836800000	1585699199999	2020-25
+2020-30	Season	2	1593561600000	1601510399999	2020-30
+2020-37	Season	2	1577836800000	1590969599999	2020-37
+2020-40	Season	2	1577836800000	1593561599999	2020-40
+2020-41	Season	2	1593561600000	1609459199999	2020-41
+199	Decade	2	631152000000	946684799999	199
+202	Decade	2	1577836800000	1893455999999	202
+-005	Decade	2	-63745056000000	-63429523200001	-005
+199?	Decade	2	631152000000	946684799999	199?
+199~	Decade	2	631152000000	946684799999	199~
+199%	Decade	2	631152000000	946684799999	199%