security: access control for particles (#169)

* setup firebase custom token

* docs

* docs

* feat: allow admin removing members from a network

* fix: properly handle fallback avatar and names

This is especially helpful in the case of members who were removed from
a network

go/internal/network/repository.go

@@ -47,6 +47,7 @@ type repository interface {
 	getNetworksForHuman(ctx context.Context, humanId string) ([]*Network, error)
 	isMember(ctx context.Context, networkID, humanId string) (bool, error)
 	listAll(ctx context.Context) ([]*Network, error)
+	listAllMemberships(ctx context.Context) (map[string][]string, error)
 
 	// Invitations
 	createInvitation(ctx context.Context, networkID, email string) error
@@ -232,6 +233,27 @@ func (r *repositoryImpl) isMember(ctx context.Context, networkID, humanId string
 	return isMember, err
 }
 
+// listAllMemberships returns humanId -> networkIds for every human with at
+// least one membership. Humans with zero memberships are absent from the map;
+// callers layer them in separately.
+func (r *repositoryImpl) listAllMemberships(ctx context.Context) (map[string][]string, error) {
+	rows, err := r.pool.Query(ctx, `SELECT human_id, network_id FROM network_members`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	out := map[string][]string{}
+	for rows.Next() {
+		var humanId, networkId string
+		if err := rows.Scan(&humanId, &networkId); err != nil {
+			return nil, err
+		}
+		out[humanId] = append(out[humanId], networkId)
+	}
+	return out, rows.Err()
+}
+
 func (r *repositoryImpl) listAll(ctx context.Context) ([]*Network, error) {
 	rows, err := r.pool.Query(ctx,
 		`SELECT `+networkColumns+` FROM networks`,