U6: Build source review workspace

[breadback00-dev]

What is the work

Create the editor workspace for reviewing, correcting, approving, removing, and reordering extracted or manually entered source items before slide generation.

Planned areas:

• app/studio/[projectId]/page.tsx
• components/intake/SourceReviewPanel.tsx
• components/intake/SourceItemCard.tsx
• convex/sourceItems.ts
• components/intake/*.test.tsx
• convex/sourceItems.test.ts

Why does it matter

The product promise depends on automation with editorial control. This workspace is where agent output becomes trusted carousel-ready content instead of unreviewed generated material.

What does done mean

• Editors can inspect extracted/manual source items as cards.
• Missing fields, ambiguous values, image state, and approval state are visible.
• Editors can correct, approve, remove, and reorder items.
• Approved items can produce slide instances for the visual studio.

Acceptance criteria

• Editor can correct an extracted event detail and approve the item.
• Editor can reorder events and the order persists.
• Editor can remove low-quality extracted items before slide generation.
• Required unresolved fields block or warn before slide generation.
• Approved source items produce slide instances for the visual studio.

Blockers

• Blocked by U4: Build agent intake guidance and parser adapter #4.
• Blocked by U5: Add image upload and source URL handling #5.

What can make this fail

• Intake output bypasses human approval.
• Review UI hides ambiguity or missing information.
• Reordering is only visual and does not persist downstream.
• Slide generation mutates source notes unexpectedly.

How should Codex verify it

• Run source item Convex tests.
• Run SourceReviewPanel and SourceItemCard component tests.
• Test correction, approval, removal, reordering, and unresolved-required-field states.
• Add an integration test from approved source items to generated slide instances.