Pin each MusicMouse host to a deploy branch, and freeze musicmouse

musicmouse_version pointed both hosts at rearchitect-backend, a branch that only
ever existed on a laptop - so the previous commit's rework could never actually
have run. Point each host at a deploy/<host> branch on the remote instead. Those
branches are the deployment record: what is installed on that box right now,
moved with a force-push when you mean to deploy.

musicmouse (Kinderzimmer) is the reason this matters. It is in daily use and
still runs the pre-rearchitecture backend out of /opt/musicmouse_venv and
espmusicmouse/host_driver/main.py. That commit has no python-backend/
pyproject.toml, no python-backend/musicmouse.service and no web/ at all, so this
role cannot install it - and a run would have force-checked-out incompatible
code over a working device first and failed afterwards. Set
mediapi_install_kidsmusic: false there and leave it alone;
deploy/musicmouse records the commit that is installed, for rollback. Add a
stat + fail right after the checkout so the same mistake stops with an
explanation instead of failing three tasks deeper.

Also in the role:

- Install the typing game's curriculum next to config.yml. A config with a
  tippen: section refuses to start without it - curriculum_file is validated as
  must-exist - so musicdolphin's new config needs it present.

- Stop clobbering config.yml. The app writes to it at runtime: parent mode
  patches the volume keys and the remote-control page rewrites the remote:
  block. A plain copy: undid that on every run. Install-once by default, with
  -e pi_musicmouse_force_config=true to push a change deliberately.

- Fill out config-musicdolphin.yml against the current schema: library root and
  cache, an absolute static_dir (../web/dist would resolve to /media/web/dist
  from /media/musicmouse and silently serve nothing), tippen, and the volume
  range for a screen-driven instance. ha: is left commented out until the
  Wohnzimmer-oben entity ids are picked - the ones in the dev config are
  Arbeitszimmer. No mqtt: (it would publish a device of dead entities on a
  simulate-only host) and no lirc:/remote: (this host runs irserver, a serial
  daemon, not the lircd this speaks TCP to).

The curriculum is a verbatim copy of app content, so exclude it from
ansible-lint rather than reformat it away from its source.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

roles/pi_musicmouse/tasks/main.yml

@@ -42,6 +42,23 @@
     force: true
   notify: Reinstall musicmouse backend
 
+- name: Check the checkout has the layout this role knows
+  ansible.builtin.stat:
+    path: /opt/musicmouse/python-backend/pyproject.toml
+  register: pi_musicmouse_pyproject
+
+- name: Fail on a pre-rearchitecture checkout
+  ansible.builtin.fail:
+    msg: >-
+      {{ musicmouse_version }} has no python-backend/pyproject.toml, so it predates the
+      rearchitecture and this role cannot install it - the venv, the systemd unit and
+      the web/ build all live somewhere else on those commits. Point
+      musicmouse_version at a branch that has it (deploy/musicdolphin), or set
+      mediapi_install_kidsmusic to false for this host and leave whatever is installed
+      alone. Stopping here rather than failing three tasks deeper with the real reason
+      buried.
+  when: not pi_musicmouse_pyproject.stat.exists
+
 - name: Create virtualenv with Python {{ pi_musicmouse_python_version }}
   ansible.builtin.command:
     cmd: "/usr/local/bin/uv venv --python {{ pi_musicmouse_python_version }} /opt/musicmouse/.venv"
@@ -58,6 +75,17 @@
     src: "{{ pi_musicmouse_config_file }}"
     dest: /media/musicmouse/config.yml
     mode: "0644"
+    # Install-once: the app writes this file itself (parent mode's volume keys, the
+    # remote-control mapping). See pi_musicmouse_force_config in defaults.
+    force: "{{ pi_musicmouse_force_config }}"
+  notify: Restart musicmouse
+
+- name: Install tippen curriculum
+  ansible.builtin.copy:
+    src: "{{ pi_musicmouse_curriculum_file }}"
+    dest: /media/musicmouse/tippen-curriculum.yml
+    mode: "0644"
+  when: pi_musicmouse_curriculum_file | length > 0
   notify: Restart musicmouse
 
 - name: Install systemd service file (from the checked-out repo, not a copy kept here)
@@ -108,5 +136,6 @@
     daemon_reload: "yes"
 # manual steps:
 #    - set samba passwords with smbpasswd
-#    - copy music into /media/musicmouse (or via samba share)
-#    - manual patching of hassclient necessary :( loop has to be passed in, to not use running_event_loop
+#    - copy music into /media/musicmouse: scripts/sync-library.sh in the app repo, which
+#      also carries the cover and analysis cache over (or use the samba share, and let
+#      the device spend the DSP time itself)