Multi-tenancy : espaces de travail + fix auth reload (rate limiter OPTIONS)

- Modèles Organization + OrgMember, migration Alembic (SQLite compatible)
- organization_id nullable sur Document, Decision, Mandate, VotingProtocol
- Service, schéma, router /organizations + dependency get_active_org_id
- Seed : Duniter G1 + Axiom Team ; tout le contenu seed attaché à Duniter G1
- Backend : list/create filtrés par header X-Organization
- Frontend : store organizations, WorkspaceSelector réel, useApi injecte l'org
- Fix critique : rate_limiter exclut les requêtes OPTIONS (CORS preflight)
  → résout le bug "Failed to fetch /auth/me" au reload (429 sur preflight)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/routers/organizations.py

@@ -0,0 +1,96 @@
+"""Organizations router: list, create, membership."""
+
+from __future__ import annotations
+
+import uuid
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.database import get_db
+from app.models.user import DuniterIdentity
+from app.schemas.organization import OrgMemberOut, OrganizationCreate, OrganizationOut
+from app.services.auth_service import get_current_identity
+from app.services.org_service import (
+    add_member,
+    create_organization,
+    get_organization,
+    get_organization_by_slug,
+    is_member,
+    list_members,
+    list_organizations,
+)
+
+router = APIRouter()
+
+
+@router.get("/", response_model=list[OrganizationOut])
+async def get_organizations(db: AsyncSession = Depends(get_db)) -> list[OrganizationOut]:
+    """List all organizations (public — transparent ones need no auth)."""
+    orgs = await list_organizations(db)
+    return [OrganizationOut.model_validate(o) for o in orgs]
+
+
+@router.post("/", response_model=OrganizationOut, status_code=status.HTTP_201_CREATED)
+async def post_organization(
+    payload: OrganizationCreate,
+    db: AsyncSession = Depends(get_db),
+    identity: DuniterIdentity = Depends(get_current_identity),
+) -> OrganizationOut:
+    """Create a new organization (authenticated users only)."""
+    existing = await get_organization_by_slug(db, payload.slug)
+    if existing:
+        raise HTTPException(
+            status_code=status.HTTP_409_CONFLICT,
+            detail=f"Slug '{payload.slug}' déjà utilisé",
+        )
+    org = await create_organization(db, **payload.model_dump())
+    # Creator becomes admin
+    await add_member(db, org.id, identity.id, role="admin")
+    return OrganizationOut.model_validate(org)
+
+
+@router.get("/{org_id}", response_model=OrganizationOut)
+async def get_organization_detail(
+    org_id: uuid.UUID, db: AsyncSession = Depends(get_db)
+) -> OrganizationOut:
+    org = await get_organization(db, org_id)
+    if not org:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Organisation introuvable")
+    return OrganizationOut.model_validate(org)
+
+
+@router.get("/{org_id}/members", response_model=list[OrgMemberOut])
+async def get_members(
+    org_id: uuid.UUID,
+    db: AsyncSession = Depends(get_db),
+    identity: DuniterIdentity = Depends(get_current_identity),
+) -> list[OrgMemberOut]:
+    org = await get_organization(db, org_id)
+    if not org:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Organisation introuvable")
+    if not org.is_transparent and not await is_member(db, org_id, identity.id):
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Accès refusé")
+    members = await list_members(db, org_id)
+    return [OrgMemberOut.model_validate(m) for m in members]
+
+
+@router.post("/{org_id}/join", response_model=OrgMemberOut, status_code=status.HTTP_201_CREATED)
+async def join_organization(
+    org_id: uuid.UUID,
+    db: AsyncSession = Depends(get_db),
+    identity: DuniterIdentity = Depends(get_current_identity),
+) -> OrgMemberOut:
+    """Join a transparent organization."""
+    org = await get_organization(db, org_id)
+    if not org:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Organisation introuvable")
+    if not org.is_transparent:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail="Rejoindre cette organisation nécessite une invitation",
+        )
+    if await is_member(db, org_id, identity.id):
+        raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail="Déjà membre")
+    member = await add_member(db, org_id, identity.id)
+    return OrgMemberOut.model_validate(member)