fix: backward-compat + bug fixes and man-page build fix for 0.16.0

Post-0.15.0 review of the 0.15.0..HEAD range surfaced regressions and
bugs. This restores backward compatibility for existing configs/CSS,
fixes confirmed defects, and repairs the scdoc man-page build break on
master. Pango-markup tooltips are intentional and were kept.

Backward-compat restorations:
- AModule: honor legacy numeric Gdk::CursorType cursor values (int overload)
- memory: correct GiB divisor (was ~2.3% low); round bare {} placeholders
- wireplumber: scale max-volume into the linear domain so the cap works again
- idle_inhibitor: gate right/middle-click deactivate & scroll on dynamic-timeouts;
  accept both dynamic-timeout(s); widen timeout to double (no fractional truncation)
- custom: keep #custom-<name>.<class> CSS selectors working (classes on box_)
- image: don't wordexp-split a single path; fall back to the literal path
- niri/window: restore hide-when-empty (new show-empty opt-in); escape tooltip
- wlr/taskbar: plain-text tooltip when markup is disabled

Bug fixes:
- tray: fix use-after-free in onAdd; guard the watcher retry timeout
- hyprland: clamp max-windows iterator (OOB); drop duplicate language tooltip block
- niri/window: supply {col}/{max_col} args in the empty branch (fmt::format_error)
- mpris: escape {dynamic}/{player} tooltip; fix dangling player; albumArtist source
- mango: fix use-after-free race (dispatch under callback_mutex_)
- mpd: contain throwing checkErrors in noexcept idle paths (no std::terminate/UAF)
- keyboard_state: always render every lock label, with guarded defaults
- bluetooth: bound GATT ReadValue timeout, opt-in + services-resolved gating,
  preserve authoritative Battery1 percentage
- wireplumber: fix WpDevice reference leak / NULL handling
- battery, clock, dwl, wayfire, graph, custom_graph, transform, river: assorted
  crash/logic fixes

Man page / build:
- niri-workspaces: fix scdoc "indented by an amount greater than 1"
  (workspace-taskbar sub-options were mis-indented; breaks man-page build)
- document new show-empty (niri/window); correct network {txBitrate}/{rxBitrate}

Not compiled locally (no gtkmm on this host); C++ build relies on CI.
Man pages validated with scdoc 1.11.4.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/modules/wayfire/backend.cpp

@@ -168,25 +168,29 @@ auto IPC::start() -> void {
   send("window-rules/get-focused-output", {});
 
   std::thread([self = shared_from_this()] {
-    auto sock = connect();
+    try {
+      auto sock = connect();
 
-    {
-      Json::Value json;
-      json["method"] = "window-rules/events/watch";
+      {
+        Json::Value json;
+        json["method"] = "window-rules/events/watch";
 
-      pack_and_write(sock, Json::writeString(self->writer_builder, json));
-      if (self->receive(sock)["result"] != "ok") {
-        spdlog::error(
-            "Wayfire IPC: method \"window-rules/events/watch\""
-            " have failed");
-        return;
+        pack_and_write(sock, Json::writeString(self->writer_builder, json));
+        if (self->receive(sock)["result"] != "ok") {
+          spdlog::error(
+              "Wayfire IPC: method \"window-rules/events/watch\""
+              " have failed");
+          return;
+        }
       }
-    }
 
-    while (auto json = self->receive(sock)) {
-      auto ev = json["event"].asString();
-      spdlog::debug("Wayfire IPC: received event \"{}\"", ev);
-      self->root_event_handler(ev, json);
+      while (auto json = self->receive(sock)) {
+        auto ev = json["event"].asString();
+        spdlog::debug("Wayfire IPC: received event \"{}\"", ev);
+        self->root_event_handler(ev, json);
+      }
+    } catch (const std::exception& e) {
+      spdlog::error("Wayfire IPC event thread stopped: {}", e.what());
     }
   }).detach();
 }