Enhance troubleshooting section for Qdrant connection errors

[RyanCargan]

Added troubleshooting tips for (one potential cause of) 'Internal Server Error' when connecting to Qdrant, including version compatibility and Docker image pinning.

Related to RooCodeInc/Roo-Code#11885

Interactively review PR in Roo Code Cloud

[vercel]

@RyanCargan is attempting to deploy a commit to the Roo Code Team on Vercel.

A member of the Team first needs to authorize it.

[roo-code-hannes]

PR Reviewer   See task

Re-reviewed the latest delta in docs/features/codebase-indexing.mdx. The follow-up commit removed the stale pointer to Roo Code release notes, so I did not add any new inline comments. One actionable issue still remains in the updated wording.

• Remove the hard-coded qdrant/qdrant:v1.13.6 guidance from the new Qdrant troubleshooting note, or frame it as a clearly temporary example tied to affected Roo versions instead of a generally supported server version.

Previous reviews

• d702699: Review #1

_{Mention @roomote in a comment to request specific changes to this pull request or fix all unresolved issues.}

[roomote-v0]

Rooviewer   See task

No new issues found in the latest commit. The previous review's concern about the hard-coded Qdrant version remains unresolved.

• Rework the Qdrant troubleshooting note so it does not hard-code qdrant/qdrant:v1.13.6 as the example version, since this will go stale once the upstream fix ships.

Previous reviews

• d702699: Review #1

_{Mention @roomote in a comment to request specific changes to this pull request or fix all unresolved issues.}

[roo-code-hannes]

This advice is likely to go stale quickly. The linked issue is being fixed in Roo Code by bumping the client and disabling Qdrant's compatibility check, so hard-coding qdrant/qdrant:v1.13.6 here will become incorrect as soon as that release ships. We also do not publish a canonical "supported Qdrant version" in Roo Code release notes today, so the preceding instruction sends readers to information that may not exist. Can we rephrase this as a temporary workaround for affected Roo versions, or drop the exact version guidance?

_{Fix it with Roomote or mention @roomote and request a fix.}

[RyanCargan]

Yeah, suggesting the users dig into the release source code may be a bit much, even if it technically solves their problem in some cases.

But if that's the case, there isn't much for the user to do except trial & error with the dev console.

Added that bit instead in a second edit & commit.

May or may not be relevant if/when RooCodeInc/Roo-Code#11885 is resolved one way or another.