* Remove fastText support and enable numpy 2.x compatibility

FastText library has been archived since March 2024 and is no longer
maintained. This dependency was blocking numpy 2.x adoption.

Changes:
- Remove fasttext extra from setup.py dependencies
- Add deprecation warnings to fasttext.py module
- Update documentation to recommend langdetect as primary option
- Update CLI to deprecate --fasttext flag
- Add comprehensive test suite for langdetect integration
- Remove fasttext from tox.ini test configurations

Users should migrate to langdetect:
  pip install dateparser[langdetect]

Closes #1287
Closes #1251

* Update dateparser_cli/cli.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update dateparser/custom_language_detection/fasttext.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Simplify fasttext deprecation to always error

The previous approach was confusing:
- If fasttext was installed, it showed a warning but still worked
- If fasttext wasn't installed, it raised an ImportError

This creates inconsistent deprecation - users don't know if the
feature is truly deprecated or not.

Now the module:
- Always shows deprecation warning on import
- Always raises ImportError when detect_languages() is called
- Provides clear migration path to langdetect
- No functional fasttext code remains

This makes the deprecation clear and consistent.

* Remove unused module-level mock in test_language_detect

The module-level 'detect_languages' mock was defined but never used.
The MockLangDetectTest class defines its own mock as a class attribute,
and other test classes use the actual lang_detect_detect_languages function.

This cleanup removes the unused mock to avoid confusion.

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>