fix(salary): detect company column from header token, not exact match (#151)

convert_salary_excel.py detected the company column via exact membership
in COMPANY_PATTERNS, so common real-world headers like "Company Name" or
"Employer Name" were never matched. parse_sheet then returned [] for that
sheet, silently dropping it from salary_data.json (or exiting with no
output for a single-sheet file).

Route company-column detection through the existing header_matches()
token matcher (already used for count/index detection). This only adds
detections; inputs that already worked (bare "Company"/"Firma"/...) are
unaffected.

Adds a regression test in tests/test_convert_salary_excel.py that fails
on master (returns []) and passes after the fix.

tests/test_convert_salary_excel.py

@@ -87,6 +87,23 @@ class DetectColumnTypeTests(unittest.TestCase):
 
         self.assertEqual(companies[0]["categories"]["software_engineering"], {"count": 8, "index": 110.0})
 
+    def test_parse_sheet_detects_company_column_with_token_header(self):
+        # Real-world salary sheets rarely use the bare token "Company";
+        # headers like "Company Name" / "Employer Name" must still be
+        # detected as the company column (previously silently skipped -> []).
+        for header in ("Company", "Company Name", "Employer Name"):
+            with self.subTest(header=header):
+                ws = FakeWorksheet([
+                    (header, "Salary"),
+                    ("Example Corp", 105.5),
+                ])
+                companies = parse_sheet(ws)
+                self.assertEqual(len(companies), 1)
+                self.assertEqual(companies[0]["company"], "Example Corp")
+                self.assertEqual(
+                    companies[0]["categories"]["salary"], {"index": 105.5}
+                )
+
 
 if __name__ == "__main__":
     unittest.main()