Profile-generation screen: trigger session, review proposed profile, confirm before write

[Ryan-Atkinson87]

The profile-generation screen: trigger the tech-lead session, review the proposed execution profile, and confirm before it is written.

Spec: §17.5 project execution profile, §15 (profile-generation UX, phase-6 detail), §3.4.

Acceptance criteria

• Triggers the tech-lead profile-generation session for a project via the profile-generation API (Profile-generation API: trigger tech-lead session, propose, human-confirm before write #58) and shows progress while it runs (§17.5).
• Displays the proposed execution-profile.yaml for human review, with an explicit confirm and reject; the profile is written only on confirm (§17.5 human-confirm-before-write).
• Rejecting or abandoning writes nothing and returns the user cleanly; this is a consequential write action — confirm before firing.
• Loading/generating, error, and populated (proposal ready) states handled; long-running generation shows a non-blocking progress state.
• No hardcoded API URLs; WCAG 2.1 AA — the proposed profile is readable and the confirm/reject actions are clearly labelled.
• Tests: trigger calls the API; proposal renders; confirm writes via API; reject writes nothing.

Depends on: #60, #58