Log messages are lower-case event names with their details as key/value
attributes ("error" for errors), in place of formatted strings.
Loggable package take a WithLogger option as part of their "New*" call,
defaulting to slog.Default(). Each tags its lines with its `component`.
Some debug loggers print directly rather than using slog when in
terminal logging mode.
- logging: LogToFile shadowed the package-level fileLogger, so
IsFileLogger was always false and Shutdown never closed the file
- logging: replace IsJSONHandler's unsafe reflection into slog
internals with a *slog.JSONHandler type check
- cli: fail if the log file can't be opened instead of silently
logging to the terminal; return the log shutdown error from Finish
- build.sh: -X flags used the wrong module path, so the version, build
time and commit were never stamped
bwilliams