feat: relocate the codebase indexing tab

[shssoichiro]

Description

This moves the codebase indexing status from its current location underneath the Settings icon, to a new tab next to the Docs tab, inline with the others.

This improves the accessibility of the codebase index tab, making it easier to find and requiring only one click to reach. This also brings it in line with the docs indexing tab so that they are providing a more similar experience.

Additionally, this fixes the text on the disabled state to show "Enable Indexing", matching the text on the toggle in the Settings tab.

Checklist

• I've read the contributing guide
• The relevant docs, if any, have been updated or created
• The relevant tests, if any, have been updated or created

Screen recording or screenshot

Settings view looks correct with Indexing tab removed:

Codebase tab displays, and has a tooltip when hovered:

When opened, the Codebase tab displays the same contents as the current Indexing tab:

The disabled state also displays correctly and the text matches the settings toggle:

Tests

All existing tests pass, and manual verification was done (see screenshots).

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Summary by cubic

Moved the codebase indexing status to a new tab next to the Docs tab for easier access and updated the disabled state text to say "Enable Indexing".

[shssoichiro]

The CI error appears to be spurious: Downloading ripgrep failed: Error: Request failed: 403

[RomneyDa]

@shssoichiro the current direction is to slowly deprecate codebase RAG indexing, which is why this is more hidden than docs. The notch tabs are precious UX space and we've decided to not add codebase to this for now. Also, codebase indexing is designed to be in the background so the user doesn't have to think about it. If they do, there's probably an issue with the system. In which situations do you frequently find yourself visiting the indexing tab?

The copy fix (disable -> enable) would be a great fix, would love to merge that.

[shssoichiro]

The issues I've found that led to wanting this tab more visible are indeed related to codebase indexing errors. The most frequent being that the codebase indexing will fail when VSCode initially loads (the common error seems to be Cannot read properties of undefined (reading 'signal')), so I have to visit the Indexing tab, see that often there is an error, and click Re-index, and then it works. Essentially, by hiding the tab, errors are also hidden from the user.

May I ask why the codebase indexing overall is being deprecated? I know that is outside the scope of this ticket, but I'm curious as it seems like a useful feature.