Fix db integration testcases to use temp db

[kevalmahajan]

🐛 Bug-fix PR

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📌 Summary

Closes #810
Previously, test cases were unintentionally using the production (or main) database configured in the .env file. As a result, test data including tools created during tests were being written to the main DB, causing data pollution and potentially impacting the integrity of production data.

💡 Fix Description

1. All test cases now use an in-memory (mock) database, isolated from the production environment.
2. Test data is ephemeral and discarded after each test run, maintaining a clean state.
3. The .env configuration for the production database is no longer referenced during test execution.
4. Tools and other entities created during testing are now invisible in the UI or any environment tied to the main DB.

Testing 🛠️

1. Run make test.
2. Confirm that no tools are created in your main database (as configured in .env).
3. Run make serve and open the UI.
4. Ensure that no new tools appear in the UI as a result of running the test cases.

🧪 Verification

Check	Command	Status
Lint suite	make lint
Unit tests	make test
Coverage ≥ 90 %	make coverage
Manual regression no longer fails	steps / screenshots

📐 MCP Compliance (if relevant)

• Matches current MCP spec
• No breaking change to MCP clients

✅ Checklist

• Code formatted (make black isort pre-commit)
• No secrets/credentials committed

[crivetimihai]

I believe this is already fixed in main, can you check and rebase please?