Memories are leaking between repositories

### Describe the bug

Today I have had a strange situation. I created a new git repository, checked it out and then asked copilot to add some basic instructions and project setup.

Out of the nowhere, it mumbled about some "facts stored in the memory" (of course there are none because the repo is fresh!) that seem to be part of a different (similar named) repository...

### Affected version

_No response_

### Steps to reproduce the behavior

_No response_

### Expected behavior

_No response_

### Additional context

_No response_

Start by reproducing the report with a fresh repository whose name resembles another repository, then trace where Copilot CLI reads and associates stored memories with repositories. The issue is done when memories from one repository cannot appear in another and the behavior is covered by a regression test.

Written by the indexing model from the issue text.