fix: resolve workspace file browser to groves/ instead of projects/

[ptone]

Summary

• Fix: hubManagedProjectPath() now resolves to ~/.scion/groves/<slug>/ (the actual git checkout mounted as /workspace in agents) instead of ~/.scion/projects/<slug>/ (which only contains project metadata and Telegram plugin downloads)
• Fallback preserved: If groves/ has no workspace content, falls back to projects/ for backward compatibility
• Default changed: When neither directory has content, defaults to groves/ path instead of projects/

Fixes issue 130

Test plan

• Updated TestHubManagedProjectPath — default path now resolves to groves/
• Added TestHubManagedProjectPath_PrefersGrovesOverProjects — when both dirs have content, groves/ wins
• Added TestHubManagedProjectPath_FallsBackToProjectsWhenGrovesEmpty — falls back to projects/ when groves/ has no real content
• Added TestHubManagedProjectPath_DefaultsToGrovesWhenNeitherHasContent — defaults to groves/ when neither has content
• All hub package tests pass

[gemini-code-assist]

Code Review

This pull request resolves a workspace file browser path resolution issue by reversing the lookup priority in hubManagedProjectPath() to prefer the actual git checkout directory (groves/<slug>) over the metadata directory (projects/<slug>). The changes also include updated and new unit tests to verify this behavior. The review feedback suggests adding a defensive check to prevent empty slugs from resolving to parent directories, which could lead to unintended operations, along with a corresponding unit test to verify this validation.

[gemini-code-assist]

An empty slug passed to hubManagedProjectPath could resolve to the parent directory (e.g., ~/.scion/groves or ~/.scion/projects). Since hasWorkspaceContent checks if the directory contains any files other than .scion or shared-dirs, a parent directory containing other projects would return true, causing the function to incorrectly return the parent directory. This could lead to catastrophic operations (like directory deletion or overwriting) on the entire parent directory. Adding a defensive check for an empty slug prevents this.

Suggested change

	func hubManagedProjectPath(slug string) (string, error) {
	globalDir, err := config.GetGlobalDir()
	func hubManagedProjectPath(slug string) (string, error) {
	if slug == "" {
	return "", errors.New("project slug cannot be empty")
	}
	globalDir, err := config.GetGlobalDir()

[gemini-code-assist]

Add a unit test to verify that hubManagedProjectPath returns an error when an empty slug is provided, ensuring the defensive check works as expected.

	// When neither has content, should default to groves/
	path, err := hubManagedProjectPath(slug)
	require.NoError(t, err)
	assert.Equal(t, grovesDir, path, "should default to groves path when neither dir has workspace content")
}

func TestHubManagedProjectPath_EmptySlug(t *testing.T) {
	_, err := hubManagedProjectPath("")
	assert.Error(t, err)
	assert.Contains(t, err.Error(), "project slug cannot be empty")
}