feat: improve background startup and launcher control

Detach --background launches from terminals with quieter runtime output, make wrapper/plugin overlay start explicit, and allow trailing commas in JSONC configs for safer hot-reload edits. Includes pending Anki/docs/backlog updates in this unreleased batch.

src/core/services/cli-command.test.ts

@@ -5,6 +5,7 @@ import { CliCommandServiceDeps, handleCliCommand } from './cli-command';
 
 function makeArgs(overrides: Partial<CliArgs> = {}): CliArgs {
   return {
+    background: false,
     start: false,
     stop: false,
     toggle: false,