feat(inbox): migrate CRM Inbox to @insignia/iios-messaging-ui SDK

Replace the bespoke in-CRM inbox with the SDK's <Inbox>, driven by a new
CrmInboxAdapter over the be-crm data door (crm.inbox.* + crm.mail.*).
Demo mode falls back to the SDK MockInboxAdapter. Maps --miu-* tokens for
.miu-inbox to the CRM theme.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

package-lock.json

@@ -1030,7 +1030,7 @@
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       "version": "0.1.0",
       "resolved": "file:../iios/packages/iios-messaging-ui/insignia-iios-messaging-ui-0.1.0.tgz",
-      "integrity": "sha512-B6Vzb75lBv4W3ZuKE4muMSz/OyUrE0NxImUI6sHaCBby5xveHVyanPiwkxiaqg9zZPYQMYiZRMONYwlNqyJvig==",
+      "integrity": "sha512-RoXEI/SgzYM2Zj+XvwNkc3rrDQ5kDa/oqsCo2wkZxwRs3bVHJuRoQR+c713wgaWK+MmqIg0cetXQ//rfJvpBbg==",
       "peerDependencies": {
         "@insignia/iios-kernel-client": "*",
         "react": ">=18"