Remove the no-op MAINTENANCE_MODE setting (closes #317)

MAINTENANCE_MODE did nothing but make the healthcheck JSON report maintenanceMode: true; no request was ever served differently, so an operator who set it expecting requests to be refused got nothing. It is removed from the configuration, the startup configuration log line, the healthcheck JSON, the README and the Settings page, together with the uncalled Server.MaintenanceMode method and the healthcheck's dependency on the configuration. A leftover value in an environment is ignored like any other unknown variable.

Model: opus-5-5

internal/healthcheck/healthcheck.go

@@ -7,7 +7,6 @@ import (
 	"time"
 
 	"go.uber.org/fx"
-	"sneak.berlin/go/webhooker/internal/config"
 	"sneak.berlin/go/webhooker/internal/database"
 	"sneak.berlin/go/webhooker/internal/globals"
 	"sneak.berlin/go/webhooker/internal/logger"
@@ -18,7 +17,6 @@ type HealthcheckParams struct {
 	fx.In
 
 	Globals  *globals.Globals
-	Config   *config.Config
 	Logger   *logger.Logger
 	Database *database.Database
 }
@@ -64,7 +62,6 @@ func (s *Healthcheck) Healthcheck() *Response {
 		UptimeHuman:   s.uptime().String(),
 		Appname:       s.params.Globals.Appname,
 		Version:       s.params.Globals.Version,
-		Maintenance:   s.params.Config.MaintenanceMode,
 	}
 
 	return resp
@@ -78,7 +75,6 @@ type Response struct {
 	UptimeHuman   string `json:"uptimeHuman"`
 	Version       string `json:"version"`
 	Appname       string `json:"appname"`
-	Maintenance   bool   `json:"maintenanceMode"`
 }
 
 func (s *Healthcheck) uptime() time.Duration {