feat(admin): organizations — logos, memberships, sponsorships

[cdcore09]

Summary

Admin surface for managing organizations: logo uploads, recurring org memberships, and per-event sponsorships. Schema already in place (organizations.logo_* columns, org_memberships, event_sponsorships); this issue is the UI + storage wiring.

Requirements

• Brainstorming → spec under docs/superpowers/specs/.
• Provision the usrse-organization-logos R2 bucket; uncomment the binding in wrangler.jsonc and fill in ORGANIZATION_LOGOS_PUBLIC_URL (the binding was deferred in commit d1140c8).
• /admin/orgs — searchable list with active-membership and active-sponsorship facets.
• /admin/orgs/:id — detail view: edit name / slug / shortName / url, upload primary + dark + mark logos with consent capture, manage org_memberships rows (tier + dates), manage event_sponsorships rows.
• Logo upload flow: file or URL import to R2, persist logo_storage_key, gate display on logo_usage_consent truthiness.
• Membership lifecycle: open / renew / close, with renewal_due_at for the dashboard tile.
• Public surface follow-on: /about/sponsors page becomes data-driven from event_sponsorships once this lands.

Context

Foundation must ship first (#1956). Phase 2 schema (4a89a55) added all the relevant columns and tables; nothing is wired to UI yet.

Implementation Notes

• Policy: canEditOrganization is staff+. Future: an org-rep role could earn scoped edit on their own org.
• OrgLogo component already falls back to InitialsHex — once real logos start landing, the public surface picks them up automatically.
• Sponsor tier enum: platinum / gold / silver / bronze / supporter / in_kind.