Give each Molecule scenario its own Ansible home

Scenarios install their Galaxy dependencies with `force: true`, so two roles
running at once re-extract the same collections and roles into ~/.ansible and
pull them out from under each other mid-play. It surfaces as a collection that
was working moments earlier going missing:

  the connection plugin 'community.docker.docker' was not found

Found while running five scenarios in parallel, where it cost a run.

ANSIBLE_HOME relocates both `collections/` and `roles/`, so one variable covers
both halves; the scenarios' ANSIBLE_ROLES_PATH workaround now follows it rather
than hardcoding ~/.ansible/roles. Left alone if already set, and unset in CI,
where each role runs in its own job and has nothing to collide with.

Verified by removing var/molecule-ansible-home entirely and running
matrix-alertmanager-receiver from cold: green through idempotence, with the
collections and roles landing under the per-role directory - which also shows
nothing was quietly relying on the shared ~/.ansible being populated.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SEH3vxYSQ5SV4N5z61eyGT

roles/custom/matrix-alertmanager-receiver/molecule/default/molecule.yml

@@ -59,7 +59,7 @@ provisioner:
           molecule-room: "!molecule-room-id:molecule.local"
   env:
     # Workaround for https://github.com/ansible/molecule/issues/4391
-    ANSIBLE_ROLES_PATH: ${MOLECULE_PROJECT_DIRECTORY}/../..:/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:~/.ansible/roles
+    ANSIBLE_ROLES_PATH: ${MOLECULE_PROJECT_DIRECTORY}/../..:/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:${ANSIBLE_HOME:-~/.ansible}/roles
 scenario:
   test_sequence:
     - dependency

roles/custom/matrix-bot-baibot/molecule/default/molecule.yml

@@ -75,7 +75,7 @@ provisioner:
         matrix_bot_baibot_config_agents_static_definitions_anthropic_config_text_generation_max_context_tokens: 56789
   env:
     # Workaround for https://github.com/ansible/molecule/issues/4391
-    ANSIBLE_ROLES_PATH: ${MOLECULE_PROJECT_DIRECTORY}/../..:/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:~/.ansible/roles
+    ANSIBLE_ROLES_PATH: ${MOLECULE_PROJECT_DIRECTORY}/../..:/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:${ANSIBLE_HOME:-~/.ansible}/roles
 scenario:
   test_sequence:
     - dependency

roles/custom/matrix-bot-matrix-reminder-bot/molecule/default/molecule.yml

@@ -80,7 +80,7 @@ provisioner:
         matrix_bot_matrix_reminder_bot_data_store_path: /matrix/matrix-reminder-bot/data/store
   env:
     # Workaround for https://github.com/ansible/molecule/issues/4391
-    ANSIBLE_ROLES_PATH: ${MOLECULE_PROJECT_DIRECTORY}/../..:/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:~/.ansible/roles
+    ANSIBLE_ROLES_PATH: ${MOLECULE_PROJECT_DIRECTORY}/../..:/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:${ANSIBLE_HOME:-~/.ansible}/roles
 scenario:
   test_sequence:
     - dependency

roles/custom/matrix-bridge-heisenbridge/molecule/default/molecule.yml

@@ -57,7 +57,7 @@ provisioner:
         matrix_bridge_heisenbridge_base_path: /matrix/heisenbridge
   env:
     # Workaround for https://github.com/ansible/molecule/issues/4391
-    ANSIBLE_ROLES_PATH: ${MOLECULE_PROJECT_DIRECTORY}/../..:/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:~/.ansible/roles
+    ANSIBLE_ROLES_PATH: ${MOLECULE_PROJECT_DIRECTORY}/../..:/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:${ANSIBLE_HOME:-~/.ansible}/roles
 scenario:
   test_sequence:
     - dependency

roles/custom/matrix-bridge-hookshot/molecule/default/molecule.yml

@@ -105,7 +105,7 @@ provisioner:
         matrix_bridge_hookshot_identifier: matrix-hookshot
   env:
     # Workaround for https://github.com/ansible/molecule/issues/4391
-    ANSIBLE_ROLES_PATH: ${MOLECULE_PROJECT_DIRECTORY}/../..:/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:~/.ansible/roles
+    ANSIBLE_ROLES_PATH: ${MOLECULE_PROJECT_DIRECTORY}/../..:/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:${ANSIBLE_HOME:-~/.ansible}/roles
 scenario:
   test_sequence:
     - dependency

roles/custom/matrix-bridge-mautrix-discord/molecule/default/molecule.yml

@@ -88,7 +88,7 @@ provisioner:
         matrix_bridge_mautrix_discord_data_path: /matrix/mautrix-discord/data
   env:
     # Workaround for https://github.com/ansible/molecule/issues/4391
-    ANSIBLE_ROLES_PATH: ${MOLECULE_PROJECT_DIRECTORY}/../..:/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:~/.ansible/roles
+    ANSIBLE_ROLES_PATH: ${MOLECULE_PROJECT_DIRECTORY}/../..:/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:${ANSIBLE_HOME:-~/.ansible}/roles
 scenario:
   test_sequence:
     - dependency

roles/custom/matrix-bridge-mautrix-meta-messenger/molecule/default/molecule.yml

@@ -101,7 +101,7 @@ provisioner:
         matrix_bridge_mautrix_meta_messenger_data_path: /matrix/mautrix-meta-messenger/data
   env:
     # Workaround for https://github.com/ansible/molecule/issues/4391
-    ANSIBLE_ROLES_PATH: ${MOLECULE_PROJECT_DIRECTORY}/../..:/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:~/.ansible/roles
+    ANSIBLE_ROLES_PATH: ${MOLECULE_PROJECT_DIRECTORY}/../..:/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:${ANSIBLE_HOME:-~/.ansible}/roles
 scenario:
   test_sequence:
     - dependency

roles/custom/matrix-bridge-mautrix-whatsapp/molecule/default/molecule.yml

@@ -63,7 +63,7 @@ provisioner:
         matrix_bridge_mautrix_whatsapp_data_path: /matrix/mautrix-whatsapp/data
   env:
     # Workaround for https://github.com/ansible/molecule/issues/4391
-    ANSIBLE_ROLES_PATH: ${MOLECULE_PROJECT_DIRECTORY}/../..:/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:~/.ansible/roles
+    ANSIBLE_ROLES_PATH: ${MOLECULE_PROJECT_DIRECTORY}/../..:/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:${ANSIBLE_HOME:-~/.ansible}/roles
 scenario:
   test_sequence:
     - dependency