05-add-permissions.md

Before implementing, review 00-project-architecture.md and use it as the architecture baseline. Follow it by default, deviate only when necessary.

Task 05: Implement a simple demo-only project permissions layer.

Scope:

• sign-in based on the existing users table
• initial sign-in must be presented as a modal gate on app load
• project access resolution through project_members
• project-level viewer/editor permissions resolved from the user's role in project_members
• projects list visibility based on membership
• create project UI for the current demo user
• minimal member management UI

Rules:

• keep the auth model demo-only and lightweight
• keep sign-in demo-only (user selection via dropdown is acceptable)
• use the existing schema from step 03
• use project_members.user_id -> users.id, not username-based joins
• do not redesign the read or CRUD architecture introduced in steps 03 and 04
• derive Gantt readOnly mode from the resolved project membership role
• show only projects available to the current demo user through project_members
• do not add passwords, sessions, or production-style authentication flows

Append to build-log.md the full request and full response after completion (append only, do not modify existing entries).