refactor(gateway): retire the standalone node pairing store (#103120)

* refactor(gateway): fold node pairing store into device records

* docs+cli: retire standalone node pairing store references

* test(infra): respec node pairing as device-backed surface approvals

* test(infra): assemble migration token fixtures dynamically

* fix(pairing): preserve node surface across device re-approval, strip legacy tokens in CLI JSON

* test(gateway): drop retired node token from pairing fixtures

* chore(protocol): regenerate Swift models, drop dead pairing-pending module

docs/refactor/database-first.md

@@ -2146,8 +2146,7 @@ Add a repo check that fails new runtime writes to legacy state paths:
 - `devices/pending.json`
 - `devices/paired.json`
 - `devices/bootstrap.json`
-- `nodes/pending.json`
-- `nodes/paired.json`
+- `nodes/pending.json` / `nodes/paired.json` (retired 2026.7: folded into `devices/paired.json` at gateway startup)
 - `identity/device.json`
 - `identity/device-auth.json`
 - `push/web-push-subscriptions.json`