Logging: structured slog messages throughout, and WithLogger options so callers choose the logger

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.

internal/cli/config/init.go

@@ -19,13 +19,13 @@ func commandInit() *cobra.Command {
 		Args:  cobra.MatchAll(cobra.MinimumNArgs(0), cobra.MaximumNArgs(1)),
 		Short: "Create an empty configuration file",
 		PersistentPreRun: func(cmd *cobra.Command, args []string) {
-			slog.Debug("config.init.PersistentPreRun")
+			slog.Debug("command persistent pre-run", "command", "config.init")
 		},
 		PersistentPostRun: func(cmd *cobra.Command, args []string) {
-			slog.Debug("config.init.PersistentPostRun")
+			slog.Debug("command persistent post-run", "command", "config.init")
 		},
 		RunE: func(cmd *cobra.Command, args []string) error {
-			slog.Debug("config.init.Run")
+			slog.Debug("command run", "command", "config.init")
 
 			if err := cobra.MinimumNArgs(0)(cmd, args); err != nil {
 				return err