Fix provider skill discovery typeahead

[brsbl]

Summary

• discover personal/project provider skills across Claude and Codex storage paths, including enabled plugins, system skills, manifest-declared components, plugin-root SKILL.md files, and user-origin symlinked skill installs
• keep project-origin symlinked skills skipped and prevent project/local Claude installed plugins from leaking into user-only discovery
• show parent skill/plugin names in compact Read SKILL.md timeline titles, use the typeahead Zap icon for skill reads, and add a dedicated Ladle story covering supported skill read path shapes

Validation

• pnpm exec turbo run test --filter=@bb/host-daemon -- command-discovery
• pnpm exec turbo run test --filter=@bb/thread-view -- timeline-row-title
• pnpm exec turbo run test --filter=@bb/app -- thread-timeline-rows
• pnpm exec turbo run typecheck --filter=@bb/host-daemon
• pnpm exec turbo run typecheck --filter=@bb/thread-view
• pnpm exec turbo run typecheck --filter=@bb/app
• git diff --check origin/main...HEAD

Ladle

• Running locally: http://localhost:62003/?story=thread--timeline--rows--tool--skill-reads
• Story: thread/timeline/rows/Tool / Skill Reads

Review

• $review found one P1 around project/local Claude installed plugins leaking into cwd: null discovery; fixed with scoped filtering and a regression test.