Fix become-precedence bug, dead Tailscale install path, and make meshcore config self-sufficient

- ansible_become: true as a group_vars connection variable silently took
  precedence over every task-level `become: false` in this repo, so
  every "unprivileged" task (pipx installs, user script deploys,
  legacy .env.local writes) was actually running as root the whole
  time. Move become to a play-level keyword in site.yml instead, which
  correctly loses to a task's own become: false. Also stop relying on
  ansible_env.HOME (which reflected root's home once facts were
  gathered under the old broken setup) and use /home/{{ remote_user }}
  directly, with explicit owner/group so ownership self-heals.
- meshcore_capture: 99-user.toml.j2 now defines every broker
  (including letsmesh-us/eu) fully rather than assuming
  config.d/10-letsmesh.toml was auto-installed — that preset only gets
  created on some install paths (fresh install) and not others
  (migrate), so the old partial-override form silently dropped
  brokers on migrated nodes.
- base: install libffi-dev/pkg-config on armv6 (Pi Zero W) — cffi has
  no prebuilt wheel for that architecture and fails to compile
  without the headers.
- dm-ashwell: migrated off the legacy layout to the current
  installer's system-service layout; drop its layout override now
  that it matches the group default.
- meshcore-capture-update.sh: fix a YAML folded scalar (>-) collapsing
  the shebang and command onto one line, corrupting the script.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

ansible/roles/meshcore_capture/templates/99-user.toml.j2

@@ -1,9 +1,10 @@
 # MeshCore Packet Capture - user overrides
 # Managed by Ansible - local changes will be overwritten on next playbook run
 #
-# [[broker]] tables merge by name across config.d/*.toml, so the letsmesh-us
-# and letsmesh-eu entries below only add owner identity to the connection
-# details already installed as config.d/10-letsmesh.toml.
+# Defines every broker fully (not relying on config.d/10-letsmesh.toml being
+# auto-installed) — whether that preset exists depends on which path the
+# installer took (fresh install vs migrate), so a partial override here would
+# silently no-op on nodes where it wasn't created.
 
 [general]
 iata = "{{ packetcapture_iata }}"
@@ -22,17 +23,45 @@ advert_interval_hours = {{ packetcapture_advert_interval_hours }}
 owner_public_key = "{{ packetcapture_owner_public_key }}"
 owner_email = "{{ packetcapture_owner_email }}"
 
+# LetsMesh.net Packet Analyzer (US)
 [[broker]]
 name = "letsmesh-us"
+enabled = true
+server = "mqtt-us-v1.letsmesh.net"
+port = 443
+transport = "websockets"
+keepalive = 120
+qos = 0
+retain = true
+
+[broker.tls]
+enabled = true
+verify = true
 
 [broker.auth]
+method = "token"
+audience = "mqtt-us-v1.letsmesh.net"
 owner = "{{ packetcapture_owner_public_key }}"
 email = "{{ packetcapture_owner_email }}"
 
+# LetsMesh.net Packet Analyzer (EU)
 [[broker]]
 name = "letsmesh-eu"
+enabled = true
+server = "mqtt-eu-v1.letsmesh.net"
+port = 443
+transport = "websockets"
+keepalive = 120
+qos = 0
+retain = true
+
+[broker.tls]
+enabled = true
+verify = true
 
 [broker.auth]
+method = "token"
+audience = "mqtt-eu-v1.letsmesh.net"
 owner = "{{ packetcapture_owner_public_key }}"
 email = "{{ packetcapture_owner_email }}"