chore: establish local platform baseline

migrations/000028_rtc_credential_metadata.up.sql

@@ -0,0 +1,17 @@
+BEGIN;
+
+ALTER TABLE rtc_task
+    ADD COLUMN credential_issued_at timestamptz NOT NULL DEFAULT now(),
+    ADD COLUMN credential_expires_at timestamptz NOT NULL DEFAULT (now() + interval '5 minutes');
+
+UPDATE rtc_task rt
+SET credential_issued_at = rt.created_at,
+    credential_expires_at = GREATEST(c.allocation_expires_at, rt.created_at + interval '1 second')
+FROM conversation c
+WHERE c.id = rt.conversation_id;
+
+ALTER TABLE rtc_task
+    ADD CONSTRAINT rtc_credential_expiry_after_issue
+    CHECK (credential_expires_at > credential_issued_at);
+
+COMMIT;