feat: add Applications API support

[innomaxx]

Closes #159

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.33%. Comparing base (f3bca05) to head (cf227af).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #267      +/-   ##
============================================
+ Coverage     93.30%   93.33%   +0.03%     
- Complexity     1840     1846       +6     
============================================
  Files           169      171       +2     
  Lines          4969     4986      +17     
============================================
+ Hits           4636     4653      +17     
  Misses          333      333              

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[Copilot]

Pull request overview

Adds support for Crowdin Applications API endpoints for managing custom application data.

Changes:

• Introduces ApplicationApi with get/add/update/delete/edit methods.
• Adds ApplicationData model for arbitrary application-defined payloads.
• Registers the new API service and adds unit tests for API/model behavior.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/CrowdinApiClient/Api/ApplicationApi.php	Adds Applications API endpoint wrappers.
src/CrowdinApiClient/Model/ApplicationData.php	Adds a model for application data payloads.
src/CrowdinApiClient/Crowdin.php	Registers the application service.
tests/CrowdinApiClient/Api/ApplicationApiTest.php	Adds tests for Applications API methods.
tests/CrowdinApiClient/Model/ApplicationDataTest.php	Adds tests for generic data access on ApplicationData.

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[innomaxx]

@andrii-bodnar please review and merge