fix: handle spaced KSEI PDF headers (SHARE CODE vs SHARE_CODE)

Newer KSEI above1 PDFs use spaces in column headers (SHARE CODE,
INVESTOR NAME, INVESTOR CLASSIFICATION) instead of the underscored
form (SHARE_CODE, INVESTOR_NAME, INVESTOR_TYPE) that the parser
schema markers expected.  This caused valid holder-register PDFs to
be misclassified as LegacyAboveFivePercent (false positive on
REKENING TAMPUNGAN KSEI text in the data), blocking import.

Changes:
- Add normalize_stext_for_classification() that replaces spaces with
  underscores inside text="..." attributes before schema marker
  matching, so both old and new header layouts are recognized
- Add INVESTOR_CLASSIFICATION to HOLDER_REGISTER_SCHEMA_MARKERS and
  HEADER_LABELS to match the renamed column
- Update ANNOUNCEMENT_WRAPPER and ABOVE_FIVE marker constants to use
  underscores (matching the normalized text)
- Add test fixture and test case for the spaced-header layout
- Bump version to 0.2.3

Tested against the live June 2026 KSEI PDF (as_of 2026-05-29):
  idx ownership import --url <latest-pdf-url>
  -> Imported 7124 rows for 956 tickers (as of 2026-05-29)

Cargo.lock

@@ -711,7 +711,7 @@ dependencies = [
 
 [[package]]
 name = "idx-cli"
-version = "0.2.2"
+version = "0.2.3"
 dependencies = [
  "assert_cmd",
  "chrono",