Route IRC_SERVER_PASSWORD/IRC_NICKSERV_PASSWORD, LINE_CHANNEL_ACCESS_TOKEN/
LINE_CHANNEL_SECRET, TEAMS_GRAPH_ACCESS_TOKEN/TEAMS_CLIENT_SECRET and
MATTERMOST_TOKEN reads at __init__/availability/standalone-send time through
a module-level _get_scoped_secret helper (get_secret, UnscopedSecretError ->
os.getenv fallback), mirroring whatsapp_common._get_wsecret / Slack #59739.
Scoped miss returns the default — no cross-profile environ borrow.
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