Unify plugin feedback into one receipt inbox

[mattheliu]

What changed

• replace multiple permanent feedback surfaces with one lightweight 体验回执 entry
• add frontend plugin selection from the rc.6 Host inventory
• let the Agent prepare a finite-enum local draft without upload capability
• add preview revision, cancellation, persistent receipt history, unread state, and progress steps
• keep contextual thumbs below the relevant Agent reply as a non-permanent shortcut
• document and test the zero-log privacy boundary

Why

The previous command-first flow was too heavy and fragmented. This keeps selection, feedback confirmation, and progress in one small receipt surface while retaining the existing closed v3 upload packet.

User impact

Users can pick the affected plugin, preview exactly what will be sent, change or cancel the draft, explicitly confirm transmission, and later see aggregation/fix progress from the same entry. No task, conversation, prompt, reply, log, stack, file, path, environment, or identity field is accepted by the feedback protocol.

Validation

• pnpm test:all
• 35 plugin/client/privacy tests
• 10 backend tests
• real DSH 0.1.0-rc.6 pack/install/boot/remove lifecycle
• application-browser flow: one entry → select plugin → thumbs → preview → revise/cancel → send → persistent progress