Add confirmed category summaries

[mattheliu]

What changed

• upgrade the closed feedback protocol to v3 with one task-agnostic category enum
• add a finite-enum Agent preview tool that has no storage or network side effects
• make the Web result card collect experience plus category and show the complete preview before a separate submit action
• reject free-text summaries while generating readable summaries from a fixed local/server template
• aggregate by category and publish only thresholded category summaries to GitHub
• keep historical v1/v2 files and tables isolated and add dedicated v3 local files and PostgreSQL tables

Why

Plugin authors need more direction than a bare good/bad signal, while users need assurance that their current task, conversation, logs, and error details cannot enter the feedback path. A closed category vocabulary provides useful product context without opening a free-text exfiltration channel.

User impact

Users now choose one of eight broad experience areas, review every readable field locally, and explicitly confirm the upload. The Agent can prepare a fixed-template preview but cannot publish it. Network transport metadata remains outside the payload guarantee and is documented honestly.

Validation

• pnpm test:all
• 27 plugin/unit tests passed
• 10 backend tests passed, including fixed GitHub summary coverage
• DSH 0.1.0-rc.6 package/install/Web boot/Client loader/remove E2E passed