Feature: Offline device history with delete and remote uninstall

Persist every device that has ever logged in to the Go server in a small
JSON store (devices.json, overridable with YAMA_DEVICES_FILE and capped by
YAMA_DEVICES_MAX, default 1000 newest). The store follows the users.json
convention: atomic temp-file write with fsync and rename, a 500 ms debounce
for bursts of reconnects, first_seen preserved across logins, and pruning
that evicts offline records before devices that are still connected.
Devices connected at shutdown are stamped offline before the final flush so
last_seen stays accurate across restarts.

The server advertises an offlineDevices capability and device_list now
appends historical devices that are not online, marked with online:false and
last_seen. The web UI shows an Offline checkbox after Total/Showing (state
kept in localStorage), renders offline cards dimmed and dashed, and always
lists them in the screen-wall sidebar. Older servers without the capability
keep the online-only list.

Grid and List cards gain a delete button after the terminal button, admin
only, behind a confirmation dialog. Deleting an offline device removes its
history record; deleting an online device first sends the single-byte
TOKEN_UNINSTALL command (matching the MFC OnOnlineUninstall flow) and then
removes the record too, so the device does not come back as a dead offline
entry. The agent's own disconnect then runs the existing cleanup path:
screen and terminal sub-connections are closed, the hub entry is removed,
and browsers receive device_offline to release their watch sets, wall
sessions, and stream references. Wall mode exposes no delete action.

Tests cover history persistence/pruning/recovery, offline ordering, the
device_list merge, and all three delete outcomes (offline removal, online
uninstall with a single 0x3F byte, and viewer rejection).

Co-Authored-By: deepseek-flash

server/go/web/server.go

@@ -16,6 +16,7 @@ import (
 	"unicode"
 	"unicode/utf8"
 
+	"github.com/yuanyuanxiang/SimpleRemoter/server/go/devicehistory"
 	"github.com/yuanyuanxiang/SimpleRemoter/server/go/hub"
 	"github.com/yuanyuanxiang/SimpleRemoter/server/go/logger"
 	"github.com/yuanyuanxiang/SimpleRemoter/server/go/wsauth"
@@ -30,6 +31,7 @@ type Server struct {
 	srv               *http.Server
 	hub               *hub.Hub
 	auth              *wsauth.Authenticator
+	history           *devicehistory.Store // nil → no offline devices
 	ws                *wsHub
 	allowedOrigins    []string // for WS Origin allowlist; empty = same-origin only
 	loginIPLimit      *wsauth.RateLimiter
@@ -86,6 +88,14 @@ func New(port int, log *logger.Logger, h *hub.Hub, auth *wsauth.Authenticator) *
 	return &Server{port: port, log: log, hub: h, auth: auth}
 }
 
+// WithDeviceHistory attaches the persistent device-history store. When set,
+// device_list also returns devices that have logged in before but are offline
+// now. Passing nil keeps the online-only behaviour. Safe to call before Start.
+func (s *Server) WithDeviceHistory(h *devicehistory.Store) *Server {
+	s.history = h
+	return s
+}
+
 // WithConfig applies hardening configuration. Returns the receiver for
 // chainable setup. Safe to call before Start; ignored thereafter.
 func (s *Server) WithConfig(cfg Config) *Server {
@@ -107,7 +117,7 @@ func (s *Server) Start() error {
 		return nil
 	}
 
-	s.ws = newWSHub(s.auth, s.hub, s.log).
+	s.ws = newWSHub(s.auth, s.hub, s.history, s.log).
 		withOriginAllowlist(s.allowedOrigins).
 		withLoginRateLimiters(s.loginIPLimit, s.loginUserLimit).
 		withTrustForwardedFor(s.trustForwardedFor)