Support the CLDR 49 ordinal day of month pattern field

[summeriver13]

scripts/import_cldr.py aborts on the CLDR 49 data with ValueError: Invalid length for field: 'ddd' (babel/dates.py:1809): CLDR 49 uses ddd for ordinal days of the month
("Sept 13th"), which the d field did not accept.

Changes

• babel/dates.py: accept ddd for d and format the ordinal day picked by
  Locale.ordinal_form; locales without ordinal forms fall back to a single d as the CLDR
  spec prescribes, so the day is not zero-padded.
• babel/core.py: new Locale.ordinal_day_formats property (CLDR 49 <dayOfMonth> patterns
  by ordinal plural category, {0} replaced by the day).
• scripts/import_cldr.py: import dayOfMonths for the gregorian calendar
  (dayOfMonthContext[@type="format"] / dayOfMonthWidth[@type="abbreviated"]), plus tests
  for parsing, the ordinal output and the fallback.

Verification

$ uv run python scripts/import_cldr.py <cldr-49-beta2>/common   # exit 0, 0 errors, 183 locales
$ uv run python -c "from datetime import date; from babel.dates import format_date as f; print(f(date(2026, 9, 13), 'MMM ddd, y', locale='en'))"
Sep 13th, 2026

• uv run pytest -q on the pinned CLDR 48.2 data: 7875 passed, 10 skipped, 2 xfailed.
• The new tests fail without the code change, with exactly the ValueError from the issue.

I left the second half of #1379 (cldr-exemplars-delta import) to the maintainers.

Disclosure: written with AI assistance; I reviewed the diff, ran the importer and the suite.