fix: reload/stop jail 404 + access list simulator

Task 1 — fix Stop/Reload Jail returning 404
  Root cause: reload_jail and reload_all sent an empty config stream
  (["reload", name, [], []]).  In fail2ban's reload protocol the end-of-
  reload phase deletes every jail still in reload_state — i.e. every jail
  that received no configuration commands.  An empty stream means *all*
  affected jails are silently removed from the daemon's runtime, causing
  everything touching those jails afterwards (including stop) to receive
  UnknownJailException → HTTP 404.

  Fixes:
  - reload_jail: send ["start", name] in the config stream; startJail()
    removes the jail from reload_state so the end phase commits instead of
    deletes, and un-idles the jail.
  - reload_all: fetch current jail list first, build a ["start", name]
    entry for every active jail, then send reload --all with that stream.
  - stop_jail: made idempotent — if the jail is already gone (not-found
    error) the operation silently succeeds (200 OK) rather than returning
    404, matching the user expectation that stop = ensure-stopped.
  - Router: removed dead JailNotFoundError handler from stop endpoint.

  391 tests pass (2 new), ruff clean, mypy clean (pre-existing
  config.py error unchanged).

Task 2 — access list simulator
  - Docker/simulate_accesses.sh: writes fake HTTP-scan log lines in
    custom format (bangui-access: http scan from <IP> ...) to
    Docker/logs/access.log so the bangui-access jail detects them.
  - fail2ban/filter.d/bangui-access.conf: failregex matching the above.
  - fail2ban/jail.d/bangui-access.conf: polling jail on access.log,
    same settings as bangui-sim (maxretry=3, bantime=60s).
  - .gitignore: whitelist new bangui-access.conf files.
  - Docker/fail2ban-dev-config/README.md: added "Testing the Access
    List Feature" section with step-by-step instructions and updated
    Configuration Reference + Troubleshooting.

backend/app/routers/jails.py

@@ -248,7 +248,8 @@ async def stop_jail(
     """Stop a running fail2ban jail.
 
     The jail will no longer monitor logs or issue new bans.  Existing bans
-    may or may not be removed depending on fail2ban configuration.
+    may or may not be removed depending on fail2ban configuration.  If the
+    jail is already stopped the request succeeds silently (idempotent).
 
     Args:
         request: Incoming request (used to access ``app.state``).
@@ -259,7 +260,6 @@ async def stop_jail(
         :class:`~app.models.jail.JailCommandResponse` confirming the stop.
 
     Raises:
-        HTTPException: 404 when the jail does not exist.
         HTTPException: 409 when fail2ban reports the operation failed.
         HTTPException: 502 when fail2ban is unreachable.
     """
@@ -267,8 +267,6 @@ async def stop_jail(
     try:
         await jail_service.stop_jail(socket_path, name)
         return JailCommandResponse(message=f"Jail {name!r} stopped.", jail=name)
-    except JailNotFoundError:
-        raise _not_found(name) from None
     except JailOperationError as exc:
         raise _conflict(str(exc)) from exc
     except Fail2BanConnectionError as exc: