docs: align man pages with code + fill documentation gaps (0.16.0 audit)

A full man<->code consistency audit surfaced options, format placeholders
and CSS classes that were implemented but undocumented, documented but not
implemented (some causing fmt crashes when copied from examples), and
defaults that disagreed with the code. This aligns the docs with the code
and fixes a few genuine code gaps.

Docs:
- Add the missing waybar-user(5) man page (and register it in meson.build)
- Document previously-undocumented options/placeholders/CSS across many
  modules (custom image-path/image-name/icon-size, graph_type/width/
  datapoints; battery smooth-power; wireplumber format-source/only-physical;
  mpris {position}/prefer-album-artist; network {signalStrengthApp}/compact
  bandwidth; pulseaudio {source_volume}/{source_desc}; upower {temperature}/
  {model}/{native-path}; wwan {power_state}/{imei}; tray ignore-list; and
  many CSS state classes: .sink-muted, .source-muted, .workspace-hover, etc.)
- Correct documented defaults to match the code (hyprland format {name},
  gamemode {count}, cpu-graph interval 5, cava input_delay 4, niri taskbar
  icon-size 16, disk/gps/wayfire formats, menu-actions object type, ...)
- Remove placeholders/options that do not apply (custom-graph {icon}/format/
  format-icons/rotate) and fix crashing examples (wwan {mode}, gps
  format-no-fix); note cava background/foreground/continuous_rendering are
  cava-config-file options

Code:
- bluetooth: accept the documented `controller` key as a synonym of
  `controller-alias` (the option was silently ignored)
- mango/workspaces: supply the documented `{name}` fmt arg (was missing ->
  fmt::format threw)
- privacy: read `tooltip` as a bool (was guarded on isString(), so the
  documented `tooltip: false` was silently ignored)

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

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

man/waybar-custom.5.scd

@@ -145,6 +145,18 @@ Addressed by *custom/<name>*
 	default: false ++
 	Enables this module to consume all left over space dynamically.
 
+*image-path*: ++
+	typeof: string ++
+	Path to an image file to display in the module.
+
+*image-name*: ++
+	typeof: string ++
+	Name of a themed icon to display in the module.
+
+*icon-size*: ++
+	typeof: integer ++
+	The size (in pixels) of the image set via *image-path* or *image-name*.
+
 # RETURN-TYPE
 
 When *return-type* is set to *json*, Waybar expects the *exec*-script  to output its data in JSON format.
@@ -169,6 +181,8 @@ $text\\n$tooltip\\n$class*
 
 *{text}*: Output of the script.
 
+*{alt}*: The *alt* value from a json return type.
+
 *{percentage}* Percentage which can be set via a json return type.
 
 *{icon}*: An icon from 'format-icons' according to percentage.
@@ -248,3 +262,5 @@ Under the premise that interval is not defined, you can use the signal and updat
 - *#custom-<name>*
 - *#custom-<name>.<class>*
 - *<class>* can be set by the script. For more information see *return-type*
+- *.flat* and *.text-button* are always applied to the module's label.
+- *.image-button* is always applied to the module's image (see *image-path*/*image-name*).