Add public proposal draft experience

[Cyber-preacher]

Summary

• add public and private visibility controls to proposal drafts
• add public draft discovery, filtering, sharing, and read-only detail pages
• surface an author's own private and public drafts together with reusable glassy cards
• add Draft to the proposal lifecycle header and preserve the existing Proposal Pool onward flow
• distinguish Governor status from threshold-based Active Governor status across identity surfaces
• centralize publication actions, route construction, draft labels, copy-link behavior, and governance status pills

Why

Saved drafts previously existed only as private editing records. Authors could not deliberately publish work in progress, readers had no public draft surface, and repeated UI logic made visibility controls harder to keep consistent. This change gives drafts a clear public lifecycle without changing proposal submission or governance authority.

User impact

Authors can publish, unpublish, share, and continue editing drafts from My Drafts. Public drafts appear in a dedicated directory and on relevant proposal surfaces. Publishing exposes a stable snapshot while the author continues to own the editable draft. Submission still happens through the Proposal Wizard review step.

Validation

• yarn test (191 tests)
• yarn typecheck
• yarn prettier --check
• yarn build
• Playwright suite (49 journeys across supported themes and viewports)
• production-source scan for runtime mock and preview wiring

Companion work

• Requires the companion server Public Drafts PR for persistence and API support.
• Documentation is covered by the companion docs PR.