[Privacy] Create main-owned cloud upload manifest and consent token

[jinjunnn]

Parent requirement

https://github.com/jinjunnn/alpha-work/issues/10

Goal

Create a main-owned upload manifest and explicit user consent token before any local content is sent to Alpha cloud.

Acceptance criteria

• Manifest binds tenant, path scope, size, purpose, retention, and content summary.
• Renderer or agent input cannot forge or broaden consent.
• Missing directory never becomes implicit whole-project consent.
• Cancellation, preview, and packaged user-visible evidence pass.