refactor: reduce return-count complexity (#1153)

## ℹ️ Description

This refactor reduces return-count complexity for the next PLR0911
ratchet while preserving existing behavior.

No related issue.

## 📋 Changes Summary

- Extract German and English pluralization helpers while keeping
translation and prefix handling in `pluralize()`.
- Remove one early return from `check_for_updates()` by sharing the
existing final state update/save path.
- Ratchet Ruff `PLR0911` `max-returns` from 12 to 10.
- Document the one-lower discovery result: `check_for_updates()` is the
next limiter at 10 returns for `max-returns = 9`.
- No dependencies, configuration requirements, documentation updates, or
generated artifacts are introduced.

### ⚙️ Type of Change
Select the type(s) of change(s) included in this pull request:
- [ ] 🐞 Bug fix (non-breaking change which fixes an issue)
- [ ] ✨ New feature (adds new functionality without breaking existing
usage)
- [ ] 💥 Breaking change (changes that might break existing user setups,
scripts, or configurations)


## ✅ Checklist
Before requesting a review, confirm the following:
- [x] I have reviewed my changes to ensure they meet the project's
standards.
- [x] I have tested my changes and ensured that all tests pass (`pdm run
test`).
- [x] I have formatted the code (`pdm run format`).
- [x] I have verified that linting passes (`pdm run lint`).
- [x] I have updated documentation where necessary. No documentation
changes were needed.

By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice.


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Refactor**
* Reorganized pluralization logic and simplified update-checking control
flow for improved code maintainability.

* **Tests**
* Expanded test coverage for pluralization with additional German and
English language variations.

* **Chores**
  * Updated code quality configuration standards.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

pyproject.toml

@@ -292,7 +292,7 @@ max-args       = 6      # max. number of args for function / method (R0913)
 # max-attributes = 15   # TODO max. number of instance attrs for a class (R0902)
 max-branches   = 42     # max. number of branch for function / method body (R0912)
 max-locals     = 27     # max. number of local vars for function / method body (R0914)
-max-returns    = 12     # max. number of return / yield for function / method body (R0911)
+max-returns    = 10     # max. number of return / yield for function / method body (R0911)
 max-statements = 115    # max. number of statements in function / method body (R0915)
 max-public-methods = 20 # max. number of public methods for a class (R0904)