fix: Use workspacePath from instance if available in CodeIndexManager and QdrantVectorStore

[NaccOll]

#6897

In multi-folder workspaces, mimic the history and index status, binding the dialog to the CWD when creating a new ChatView. This will prevent CWD switching during a conversation and further confusion.

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Important

Use instance-specific workspacePath in CodeIndexManager and QdrantVectorStore to ensure consistent workspace handling.

• Behavior:
  • In CodeIndexManager, use this.workspacePath if available instead of getWorkspacePath() in initialize() and _recreateServices().
  • In QdrantVectorStore, use this.workspaceRoot if available instead of getWorkspacePath() in deletePointsByMultipleFilePaths().
• Classes:
  • Add workspaceRoot property to QdrantVectorStore to store the workspace path.
• Misc:
  • Ensures consistent workspace path usage in multi-folder workspaces to prevent CWD switching during operations.

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[roomote]

Thank you for your contribution! I've reviewed the changes to improve multi-folder workspace support. While the approach of using instance-specific workspace paths is good, I found some critical issues that need attention before merging.

[NaccOll]

merge into #6904