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/wsserve/command.go

@@ -22,13 +22,13 @@ func NewCommand(opts *cli.Options) *cobra.Command {
 		Use:   "wsserve",
 		Short: "Run JobSearch TCP Websocket server",
 		PersistentPreRun: func(cmd *cobra.Command, args []string) {
-			slog.Debug("wsserve.PersistentPreRun")
+			slog.Debug("command persistent pre-run", "command", "wsserve")
 		},
 		PersistentPostRun: func(cmd *cobra.Command, args []string) {
-			slog.Debug("wsserve.PersistentPostRun")
+			slog.Debug("command persistent post-run", "command", "wsserve")
 		},
 		RunE: func(cmd *cobra.Command, args []string) error {
-			slog.Debug("wsserve.Run")
+			slog.Debug("command run", "command", "wsserve")
 
 			addrOverride, _ := cmd.Flags().GetString("listen")
 			hostOverride, _ := cmd.Flags().GetString("host")
@@ -74,8 +74,8 @@ func NewCommand(opts *cli.Options) *cobra.Command {
 				stop()
 			}()
 
-			hub := websocket.NewHub(conf.Server.WebSocket, slog.Default())
-			svr := tcpserver.New(&conf.Server, hub, slog.Default())
+			hub := websocket.NewHub(conf.Server.WebSocket)
+			svr := tcpserver.New(&conf.Server, hub)
 
 			return svr.Run(ctx)
 		},