P1: screen-understanding provider 管理与真实截图验收

[CubePlus1]

Goal

Deliver the next screen-understanding milestone as a usable macOS screenshot loop rather than another configuration-only slice.

Scope

• Provider profile metadata in PostgreSQL
• Write-only API-key management through macOS Keychain
• EchoLog Web settings/provider/key administration
• Minimal EchoLogScreenCapture.app helper using ScreenCaptureKit
• Explicit one-shot screenshot test API and Web preview
• Real deployed screenshot, cleanup, plugin-doctor, and daemon-health acceptance

Parallel delivery

1. Provider/API/Keychain-client/Web track
2. Native macOS helper track
3. Integration, deployment, and real screenshot acceptance

Trellis parent: .trellis/tasks/08-11-screen-understanding-capture/

Non-goals

• Vision-model invocation or interpretation results
• Recurring/background screenshot scheduling
• Screenshot history or long-term image storage
• Cross-platform capture

Acceptance

• Raw provider keys never appear in PostgreSQL, responses, logs, argv, environment, browser storage, or fixtures.
• A real active-display screenshot is captured through the deployed signed helper, displayed as a temporary Web preview, and removed from temporary storage.
• Existing screen-time APIs remain ready and /api/health plus /api/plugins/doctor stay healthy.