added more share options and collabs

backend/migrations/0008_collab.sql

@@ -0,0 +1,31 @@
+-- Collaboration + shared cross-off ("claim") support.
+
+-- Per-list toggle: may anonymous holders of the share link cross items off?
+ALTER TABLE lists ADD COLUMN allow_guest_crossoff BOOLEAN NOT NULL DEFAULT false;
+
+-- Shared claim on an item: who crossed it off, and when. Visible to everyone
+-- who can see the list (gift-registry "this one's taken" semantics).
+ALTER TABLE items ADD COLUMN claimed_at         TIMESTAMPTZ;
+ALTER TABLE items ADD COLUMN claimed_by_user_id UUID REFERENCES users(id) ON DELETE SET NULL;
+ALTER TABLE items ADD COLUMN claimed_by_name    TEXT;
+
+-- Collaboration invite links. Each link carries the role it grants; revoking
+-- a link is just deleting the row. Accepting one creates a collaborator.
+CREATE TABLE list_invites (
+    id         UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    list_id    UUID NOT NULL REFERENCES lists(id) ON DELETE CASCADE,
+    token      TEXT NOT NULL UNIQUE,
+    role       TEXT NOT NULL CHECK (role IN ('editor', 'crosser')),
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+CREATE INDEX list_invites_list ON list_invites (list_id);
+
+-- Accepted collaborators on a list (besides the owner).
+CREATE TABLE list_collaborators (
+    list_id    UUID NOT NULL REFERENCES lists(id) ON DELETE CASCADE,
+    user_id    UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    role       TEXT NOT NULL CHECK (role IN ('editor', 'crosser')),
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    PRIMARY KEY (list_id, user_id)
+);
+CREATE INDEX list_collaborators_user ON list_collaborators (user_id);