Add e2e tests for embedding raw flag

[SamMalayek]

🧩 Summary

This PR adds a CI workflow for end-to-end embedding CLI tests (none exist today). It establishes a small, fast, reproducible baseline for validating embedding behavior (dimensions + determinism) using tiny GGUF models.

Discussion / design context: See the companion RFC in Discussions for the longer-term plan to add a native server endpoint: #16957

⚙️ What this PR includes

• A GitHub Actions job (embeddings.yml) that runs E2E embedding CLI tests with cached tiny models (e.g., TinyLlama).
• Checks output dimensions and deterministic behavior.
• Keeps runs lightweight and fast; an optional large-model stress test can be added later.

[CISC]

While testing is great I have issues with this PR:

• The CI only runs when the example code change, not when actual embedding code changes
• The tests are not testing anything likely to break, nor indeed even anything useful

To sum up; overall as a CI job this will not run when it matters, and when it is run it will not catch any problems of consequence.

Lastly, why create a new PR instead of arguing your case in the original PR and maybe iron out concerns there?

[SamMalayek]

While testing is great I have issues with this PR:

• The CI only runs when the example code change, not when actual embedding code changes
• The tests are not testing anything likely to break, nor indeed even anything useful

To sum up; overall as a CI job this will not run when it matters, and when it is run it will not catch any problems of consequence.

I kept them in examples alongside the CLI code as a pragmatic, incremental, small first step. The intent was to expand scope and relocate to tests/e2e/embedding/ once the embedding path itself was integrated into the server runtime (or simply commonized as an intermediary step). That said, I can move them now and broaden coverage to better match expectations (done).

Lastly, why create a new PR instead of arguing your case in the original PR and maybe iron out concerns there?

That PR was closed with minimal comment. So, I started this RFC: #16957

[SamMalayek]

Note: Empty force-pushes are to re-trigger the CI workflow following an intermittent failure.

[SamMalayek]

Putting this in draft while work on the very needed RFC (please see) continues: #16957