feat(app): reintroduce model context tooltip in model selector

[arvsrn]

Issue for this PR

N/A

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Reintroduces model context tooltip that was lost during model selector alignment.

How did you verify your code works?

• Ran the app locally and verified the updated UI manually
• Ran type checks locally (bun turbo typecheck)

Screenshots / recordings

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

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Hey! Your PR title reintroduce model context tooltip in model selector doesn't follow conventional commit format.

Please update it to start with one of:

• feat: or feat(scope): new feature
• fix: or fix(scope): bug fix
• docs: or docs(scope): documentation changes
• chore: or chore(scope): maintenance tasks
• refactor: or refactor(scope): code refactoring
• test: or test(scope): adding or updating tests

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