Increase TortoiseContext test coverage

[seladb]

Description

This PR adds comprehensive tests for the TortoiseContext class, covering:

• set_global_context()
• init() with config file
• Router initialization

Motivation and Context

These tests improve code coverage for the TortoiseContext class.

How Has This Been Tested?

All new tests are unit tests using pytest with the @pytest.mark.asyncio decorator where needed. Tests use in-memory SQLite databases and temporary files for config file tests.

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added the changelog accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codspeed-hq]

Merging this PR will not alter performance

✅ 24 untouched benchmarks

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_{Comparing seladb:add-context-tests (548638a) with develop (5e65d83)}

[seladb]

I'm not sure what's the error on sqlite 🤔

https://github.com/tortoise/tortoise-orm/actions/runs/22940646335/job/66743540440?pr=2138

Warning: Failed to download action 'https://api.github.com/repos/astral-sh/setup-uv/tarball/6ee6290f1cbc4156c0bdd66691b2c144ef8df19a'. Error: Response status code does not indicate success: 401 (Unauthorized). 5C00:1EAD18:1950230:6B3F969:69B251E3
Warning: Back off 22.366 seconds before retry.
Warning: Failed to download action 'https://api.github.com/repos/astral-sh/setup-uv/tarball/6ee6290f1cbc4156c0bdd66691b2c144ef8df19a'. Error: Response status code does not indicate success: 401 (Unauthorized). 5C01:16E297:1CD2D72:7A10241:69B251FA
Warning: Back off 10.901 seconds before retry.
Error: Response status code does not indicate success: 401 (Unauthorized).

[coveralls]

Pull Request Test Coverage Report for Build 22940646335

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.2%) to 83.611%

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Totals
Change from base Build 22825650456:	0.2%
Covered Lines:	11029
Relevant Lines:	12734

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💛 - Coveralls