Update type anotations

[miky-rola]

This branch improves type safety and consistency across the codebase.

• Added and refined type annotations for configs, managers, and helper functions.
• Replaced loose type checks with more explicit isinstance checks.
• Updated import paths for clarity and correctness.
• Refactored _chunks usage to use the correct variables.
• Removed redundant return in validator functions that never return.
• Unified ManagerType as a union of the supported config classes.
• Used Union, Optional, List, and Tuple from typing for backwards compatibility (pre-3.10 support).

[codecov]

Codecov Report

❌ Patch coverage is 87.55556% with 28 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.94%. Comparing base (cd8196f) to head (abd883f).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
push_notifications/webpush.py	70.58%	1 Missing and 4 partials ⚠️
push_notifications/api/rest_framework.py	85.71%	4 Missing ⚠️
push_notifications/conf/app.py	90.90%	4 Missing ⚠️
push_notifications/models.py	80.95%	4 Missing ⚠️
push_notifications/admin.py	80.00%	2 Missing ⚠️
push_notifications/apns.py	81.81%	1 Missing and 1 partial ⚠️
push_notifications/apns_async.py	85.71%	1 Missing and 1 partial ⚠️
push_notifications/fields.py	88.23%	2 Missing ⚠️
push_notifications/wns.py	77.77%	2 Missing ⚠️
push_notifications/gcm.py	85.71%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #784      +/-   ##
==========================================
+ Coverage   72.75%   72.94%   +0.18%     
==========================================
  Files          31       31              
  Lines        1259     1290      +31     
  Branches      207      214       +7     
==========================================
+ Hits          916      941      +25     
- Misses        300      301       +1     
- Partials       43       48       +5     

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[miky-rola]

@50-Course Hi kindly check it out

[50-Course]

Hi again, thanks for this! We should call this in 🚀

[jamaalscarlett]

Great job. I found some missing Optional types, but other than that this is awesome.