feat(cli): add admin REPL + commands and docs

- Add CLI entry in backend with default REPL, persistent history, aliases
- Add commands: users:list/create/verify, events:list/details/participants/checkin,
  matches:list, logs:app, logs:messages
- Support running subcommands inside REPL via .cli and run()
- Add Makefile targets: dev-cli, prod-cli, dev/prod up/down (+rebuild)
- Update README and add docs/ADMIN_CLI.md
- Add CLI tests with mocked Prisma

backend/.repl_history

@@ -0,0 +1,10 @@
+dopisz do docs/ szczegóły jakie opcje są w CLI REPL 
+exit
+Headers.
+Headers
+.cli logs
+.cli lgos
+.cli prisma:seed
+.cli events:list
+.cli users:list
+.cli users:lists