fix: restore Claude path, plugin skill, and preview scanning

[ithiria894]

Summary

• port the useful bug fixes from fix(scanner): support non-ASCII project paths and plugin-provided skills #20/fix(scanner): traverse symlinked dirs in resolveEncodedProjectPath + add tests #21 onto the current Claude harness adapter
• resolve Claude project scopes through session cwd, symlink traversal, Unicode/lossy encoded paths, and keep unresolved scopes visible
• scan Claude plugin-provided skills for user and project scopes
• make markdown-backed previews fall back to escaped text when marked fails, so skills/memories/agents do not show Failed to load preview
• stabilize e2e coverage for malformed JSON and security-status auth checks

Tests

• npm run test:unit
• npm test

Ken review: no comments.