Move custom domains onto trust centers

Custom domains previously hung off the organization. Attach them to the
trust center instead, adding default and custom domain references plus a
managed flag, and backfill existing rows. Domains now belong to a
compliance page rather than the whole organization.

Signed-off-by: Bryan Frimin <bryan@probo.com>

pkg/coredata/migrations/20260706T132923Z.sql

@@ -0,0 +1,33 @@
+-- Copyright (c) 2026 Probo Inc <hello@probo.com>.
+--
+-- Permission to use, copy, modify, and/or distribute this software for any
+-- purpose with or without fee is hereby granted, provided that the above
+-- copyright notice and this permission notice appear in all copies.
+--
+-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+-- REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+-- AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+-- INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+-- LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+-- OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+-- PERFORMANCE OF THIS SOFTWARE.
+
+ALTER TABLE custom_domains ADD COLUMN managed BOOLEAN NOT NULL DEFAULT FALSE;
+ALTER TABLE custom_domains ALTER COLUMN managed DROP DEFAULT;
+
+ALTER TABLE trust_centers ADD COLUMN default_domain_id TEXT REFERENCES custom_domains(id) ON DELETE SET NULL;
+ALTER TABLE trust_centers ADD COLUMN custom_domain_id TEXT REFERENCES custom_domains(id) ON DELETE SET NULL;
+
+UPDATE trust_centers tc
+SET custom_domain_id = o.custom_domain_id
+FROM organizations o
+WHERE o.id = tc.organization_id AND o.custom_domain_id IS NOT NULL;
+
+DELETE FROM custom_domains cd
+WHERE NOT EXISTS (
+    SELECT 1 FROM trust_centers tc
+    WHERE tc.custom_domain_id = cd.id OR tc.default_domain_id = cd.id
+);
+
+DROP INDEX IF EXISTS idx_organizations_custom_domain;
+ALTER TABLE organizations DROP COLUMN custom_domain_id;