manager: surface D-Bus call errors to the user

Connect / Forget / Set(Powered) / Scan / Disconnect / RegisterAgent /
ConnectHidden previously discarded reply errors with NULL callbacks, so
"Connecting…" could hang forever after a refused call (rfkill, busy
adapter, another agent already registered, bad credentials on a known
network). The user had no way to see the failure.

Add iwd_manager_{report,last,clear}_error and wire reply callbacks in
adapter / device / network / agent. The popup status line now appends
the latest error to the state label, and user actions (rescan, toggle,
connect, disconnect) clear it.

Scan errors that mean "already in flight" are filtered out — they're
the normal race when two scan triggers fire close together.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/iwd/iwd_device.c

@@ -3,7 +3,6 @@
 #include "iwd_props.h"
 #include "iwd_manager.h"
 #include "iwd_network.h"
-#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -186,35 +185,72 @@ _refresh_signals(Iwd_Device *d)
                      _on_ordered_networks, d, -1, "");
 }
 
+static void
+_on_scan_reply(void *data, const Eldbus_Message *msg, Eldbus_Pending *p EINA_UNUSED)
+{
+   Iwd_Device *d = data;
+   const char *en, *em;
+   if (!eldbus_message_error_get(msg, &en, &em)) return;
+   /* "AlreadyExists" / "InProgress" is the normal race when two scan
+    * triggers fire close together — don't spam the user with that. */
+   if (en && (strstr(en, "InProgress") || strstr(en, "Busy") ||
+              strstr(en, "AlreadyExists")))
+     return;
+   if (d->manager)
+     iwd_manager_report_error(d->manager, "Scan failed: %s", em ? em : en);
+}
+
 void
 iwd_device_scan(Iwd_Device *d)
 {
    if (!d || !d->station_proxy) return;
-   eldbus_proxy_call(d->station_proxy, "Scan", NULL, NULL, -1, "");
+   eldbus_proxy_call(d->station_proxy, "Scan", _on_scan_reply, d, -1, "");
+}
+
+static void
+_on_disconnect_reply(void *data, const Eldbus_Message *msg, Eldbus_Pending *p EINA_UNUSED)
+{
+   Iwd_Device *d = data;
+   const char *en, *em;
+   if (eldbus_message_error_get(msg, &en, &em) && d->manager)
+     iwd_manager_report_error(d->manager,
+                              "Disconnect failed: %s", em ? em : en);
 }
 
 void
 iwd_device_disconnect(Iwd_Device *d)
 {
    if (!d || !d->station_proxy) return;
-   eldbus_proxy_call(d->station_proxy, "Disconnect", NULL, NULL, -1, "");
+   eldbus_proxy_call(d->station_proxy, "Disconnect", _on_disconnect_reply, d, -1, "");
 }
 
+typedef struct
+{
+   Iwd_Device *d;
+   char       *ssid;
+} _Connect_Hidden_Ctx;
+
 static void
 _on_connect_hidden_reply(void *data, const Eldbus_Message *msg, Eldbus_Pending *p EINA_UNUSED)
 {
+   _Connect_Hidden_Ctx *ctx = data;
    const char *en, *em;
-   char *ssid = data;
-   if (eldbus_message_error_get(msg, &en, &em))
-     fprintf(stderr, "e_iwd: ConnectHiddenNetwork('%s') failed: %s: %s\n",
-             ssid ? ssid : "?", en, em);
-   free(ssid);
+   if (eldbus_message_error_get(msg, &en, &em) && ctx->d->manager)
+     iwd_manager_report_error(ctx->d->manager,
+                              "Connect to hidden '%s' failed: %s",
+                              ctx->ssid ? ctx->ssid : "?", em ? em : en);
+   free(ctx->ssid);
+   free(ctx);
 }
 
 void
 iwd_device_connect_hidden(Iwd_Device *d, const char *ssid)
 {
    if (!d || !d->station_proxy || !ssid || !*ssid) return;
+   _Connect_Hidden_Ctx *ctx = calloc(1, sizeof(*ctx));
+   if (!ctx) return;
+   ctx->d    = d;
+   ctx->ssid = strdup(ssid);
    eldbus_proxy_call(d->station_proxy, "ConnectHiddenNetwork",
-                     _on_connect_hidden_reply, strdup(ssid), -1, "s", ssid);
+                     _on_connect_hidden_reply, ctx, -1, "s", ssid);
 }