add invite to space feature

internal/db/migrations/00008_create_space_invitations_table.sql

@@ -0,0 +1,25 @@
+-- +goose Up
+-- +goose StatementBegin
+CREATE TABLE IF NOT EXISTS space_invitations (
+    token TEXT PRIMARY KEY NOT NULL,
+    space_id TEXT NOT NULL,
+    inviter_id TEXT NOT NULL,
+    email TEXT NOT NULL,
+    status TEXT NOT NULL CHECK (status IN ('pending', 'accepted', 'expired')),
+    expires_at TIMESTAMP NOT NULL,
+    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    FOREIGN KEY (space_id) REFERENCES spaces(id) ON DELETE CASCADE,
+    FOREIGN KEY (inviter_id) REFERENCES users(id) ON DELETE CASCADE
+);
+
+CREATE INDEX IF NOT EXISTS idx_space_invitations_email ON space_invitations(email);
+CREATE INDEX IF NOT EXISTS idx_space_invitations_space_id ON space_invitations(space_id);
+-- +goose StatementEnd
+
+-- +goose Down
+-- +goose StatementBegin
+DROP INDEX IF EXISTS idx_space_invitations_space_id;
+DROP INDEX IF EXISTS idx_space_invitations_email;
+DROP TABLE IF EXISTS space_invitations;
+-- +goose StatementEnd