refactor: remove lifetime and cwd from WorkspaceRoot

[branchseer]

TL;DR

Refactored WorkspaceRoot to use Arc<AbsolutePath> for the path field and separated the cwd field from the struct.

What changed?

• Modified WorkspaceRoot struct to use Arc<AbsolutePath> for the path field instead of a reference
• Removed the cwd field from WorkspaceRoot and made it a separate return value in find_workspace_root
• Updated find_workspace_root to return a tuple of (WorkspaceRoot, RelativePathBuf) instead of just WorkspaceRoot
• Updated all callers of find_workspace_root to handle the new return type
• Fixed all references to workspace_root.path to properly dereference the Arc when needed

How to test?

• Run the existing test suite to ensure all functionality works as expected
• Verify that workspace discovery and package graph loading work correctly
• Check that task graph generation functions properly with the new structure

Why make this change?

This change improves memory management by using Arc (Atomic Reference Counting) for the workspace path, allowing it to be shared efficiently across different components without lifetime constraints. Separating the cwd from the WorkspaceRoot struct makes the API more explicit about what belongs to the workspace definition versus contextual information about the current working directory.

[branchseer]

• feat: intergrate vite_task_plan and vite_task_graph in vite_task::session #64
• refactor: remove lifetime and cwd from WorkspaceRoot #62 👈 (View in Graphite)
• main

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