The entrypoint used jq to parse MANUAL_USER_MAPPINGS as JSON, but
ParseManualMappings() in Go uses "GiteaUsername:SlackID,GiteaUser2:SlackID2"
format. The mismatch caused "set -e" to kill the shell when jq failed
on non-JSON input, preventing the Go binary from ever starting.
Fix: replace jq JSON parsing with comma/colon splitting to match
the Go code's expected format.