Collectives P1: participation landing (ES/EN), group tree, room provisioning APIs

- 030: groups.parent_id tree + kind discriminator + group_rooms mapping
- /collectives module: create/tree/join APIs, MatrixProvisioner (open room
  public+federated, closed room E2EE-at-creation, onboarding room), NullProvisioner
  fail-soft when ARCHIVE_PROVISIONER_* unset
- web root becomes the public participation manual (ES-first + EN toggle,
  three paths: join by invite, start collective, solo account)
- participation manual content in core

docs/design/2026-10-12-collectives-architecture.md

@@ -1,5 +1,14 @@
 # Collectives architecture — participation, rooms, subcollectives, diffusion
 
+> **Status — P1 shipped (implementation note).** The three scope pillars of P1 are in:
+> `groups.parent_id`/`groups.kind`/`group_rooms` (migration `030_collectives.sql`),
+> the participation-manual landing page at the app root (`apps/web/src/app/page.tsx`, copy in
+> `packages/core/src/participation-manual.ts`), and the provisioner port + Matrix implementation
+> (`apps/api/src/collectives/`). Join-by-invite is unchanged: an invite token claims workspace
+> membership exactly as before; `GET /collectives-public/for-invite/:token` adds names-only
+> collective labelling to the join card. Room addresses in the UI, directory, and the UI/state
+> re-parenting surface remain P2+.
+
 Status: design for build (phase 1 dispatch in flight)
 Date: 2026-10-12
 Decides: landing flow, collective model, room matrix, provisioning, diffusion