Add matrix-rustpush-bridge (iMessage)

Add the matrix-rustpush-bridge role, a Matrix <-> iMessage bridge built
on the mautrix-go bridgev2 framework using RustPush (OpenBubbles backend).

Unlike the existing mautrix-imessage/wsproxy bridge, it talks directly to
Apple's push notification service, so it needs neither a running Mac nor a
wsproxy on the homeserver. Each user supplies a hardware key extracted from a
Mac through the bridge bot's login flow.

The bridge uses its own bot username and puppet namespace (rustpushbot,
rustpush_*) so it does not collide with the wsproxy iMessage bridge.

This bridge is in early development and may have stability issues.

roles/custom/matrix-bridge-rustpush/tasks/main.yml

@@ -0,0 +1,25 @@
+# SPDX-FileCopyrightText: 2026 MDAD project contributors
+# SPDX-FileCopyrightText: 2026 Jason LaGuidice
+#
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+---
+
+- tags:
+    - setup-all
+    - setup-rustpush-bridge
+    - install-all
+    - install-rustpush-bridge
+  block:
+    - when: matrix_rustpush_bridge_enabled | bool
+      ansible.builtin.include_tasks: "{{ role_path }}/tasks/validate_config.yml"
+
+    - when: matrix_rustpush_bridge_enabled | bool
+      ansible.builtin.include_tasks: "{{ role_path }}/tasks/setup_install.yml"
+
+- tags:
+    - setup-all
+    - setup-rustpush-bridge
+  block:
+    - when: not matrix_rustpush_bridge_enabled | bool
+      ansible.builtin.include_tasks: "{{ role_path }}/tasks/setup_uninstall.yml"