feat(es): support standalone months and ordinal dates

[guerrerojuli]

Summary

Adds a casual-only Spanish month-name parser modeled on the English implementation and integrates Spanish ordinal words through 31 into the existing day-first parser. Preserves numeric dates, ranges, suffixes, and original result text/index.

Behavior

Input	Mode	Result
septiembre, en septiembre	casual	September 1 at implied noon
septiembre de 2027	casual	September 1, 2027 at implied noon
setiembre, en sep	casual	September, implied day 1
primero de septiembre	casual/strict	September 1
trigésimo primero de diciembre	casual/strict	December 31
Ordinal ranges and ordinal + time	existing day-first grammar	Complete merged result
Standalone months	strict	Not parsed

Implicit years use findYearClosestToRef and the common ForwardDateRefiner. Explicit aliases preserve accented and approved ASCII ordinal spellings. Existing numeric symbol suffixes remain supported alongside Spanish letter suffixes. The standalone parser yields to day-first grammar, including rejected invalid dates and compact ranges, to prevent partial month fallbacks.

No month-first parser, normalization, dependencies, generated output, public export changes, or unrelated Spanish grammar is included. This PR is independently based on master, not stacked on the future-expression changes.

Context

Related to #478 and #628. The month-parser structure and ordinal vocabulary adapt the overlapping work proposed by @juansegnana in #628. This smaller contribution adds direct standalone-month tests and wires the vocabulary into the existing little-endian parser without importing the broader configuration refactor or other parsers.

Verification

• Focused Spanish suites: 2 suites, 9 tests passed.
• Independent fixture exercises every approved ordinal spelling; suffix/separator tests cover invalid-date fallback and compact ranges.
• Full coverage suite: 147 suites, 679 tests passed.
• CommonJS/ESM build, Prettier, git diff check, and pre-commit hooks passed.
• Independent automated review passed, explicitly checking minimalist code, no unnecessary defensive logic, and repository-pattern alignment.
• Lint limitation: upstream ESLint 9 cannot load the legacy package configuration. Legacy mode also references the removed prettier/@typescript-eslint export. A temporary corrected legacy configuration produced baseline-only errors (34 errors, 43 warnings); no configuration or dependency changes are included.