Add automated tests for prs

[ShiosOS]

Context

There is current no way to autorun tests on prs, this PR aims to add that.

This Change

• Add yml for automated github tests on prs

[chatgpt-codex-connector]

💡 Codex Review

cauldron/backend/Cauldron.Api.Tests/LeftoverEndpointsTests.cs

Line 71 in 6e98d1e

Assert.Equal(2, leftovers!.Count);

Reset database state between endpoint tests

These tests share a single TestApplicationFactory instance for the whole class, and that factory creates one SQLite file that is never cleared, so data written in one test leaks into the next. In this class, CreateLeftover_PersistsAndCanBeFetched can leave an extra row that makes GetAllLeftovers_ReturnsSortedByExpiry fail on Count == 2 depending on xUnit test order, creating flaky CI failures.

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