feat(research): add project workspace shell

[hubab1]

Summary

• add a root-toolbar entry that opens a standalone Keyword Research workspace
• add project loading, empty, retry, pagination, create, edit, and delete states
• keep project selection stable across asynchronous reloads and redact persistence errors
• avoid changing the main app sidebar while the workspace remains an optional tool

Validation

• xcodebuild test -project OpenASO.xcodeproj -scheme OpenASO -configuration Debug -destination 'platform=macOS' CODE_SIGNING_ALLOWED=NO (581 tests passed)
• plutil -lint OpenASO.xcodeproj/project.pbxproj
• git diff --check
• native visual smoke test: toolbar entry, empty workspace, and new-project editor