Fix statpanel obj_window null dereference (#22538)

* Please describe the intent of your changes in a clear fashion.
This PR addresses SERVER-PROD-75, where the `set_turf_examine_tab` and
`return_object_images` procs in the statpanels subsystem would crash due
to attempting to access `client.obj_window.atoms_to_show` when
`client.obj_window` was null.

The root cause was a lifecycle desync: `client.obj_window` is primarily
initialized within `/mob/set_listed_turf` and can be explicitly nulled
by `/datum/object_window_info/Destroy()`. However, the statpanels
subsystem would still attempt to update the turf examine tab if
`mob.listed_turf` was set, even if `client.obj_window` had become null
(e.g., after a mob transfer, relogin, or `obj_window` destruction
without a subsequent `set_listed_turf` call).

The fix involves lazy-initializing `client.obj_window` within both
`set_turf_examine_tab` and `return_object_images`. This ensures that
`client.obj_window` is always a valid `/datum/object_window_info`
instance before its properties are accessed, preventing the null
dereference crash.
* Please make sure that, in the case of mapping changes, you include
images of these changes in the PR's description.
* Please make sure to mark your PR as wip or review required by making a
comment with !wip or !review required
* If you include sprites/sounds/... (assets) that you have not created
yourself specify the license and original author below.
* Ensure that you also credit them in the appropriate location /
changelog as specified in the contributor guidelines

### Asset Licenses
The following assets that **have not** been created by myself are
included in this PR:

| Path | Original Author | License |
| --- | --- | --- |
| icons/example.dmi | ExamplePerson (Example Station) | CC0 |


Fixes SERVER-PROD-75

---------

Co-authored-by: sentry[bot] <39604003+sentry[bot]@users.noreply.github.com>
Co-authored-by: VMSolidus <evilexecutive@gmail.com>

code/controllers/subsystems/statpanel.dm

@@ -186,6 +186,11 @@ SUBSYSTEM_DEF(statpanels)
 		atoms_to_display += turf_content
 
 	/// Set the atoms we're meant to display
+	// Lazy-init: SSstatpanels can fire for a client whose obj_window was never
+	// created (mob transfer / relogin) or was nulled by /datum/object_window_info/Destroy()
+	// while mob.listed_turf survived. Without this guard we'd null-deref atoms_to_show.
+	if(!target.obj_window)
+		target.obj_window = new /datum/object_window_info(target)
 	var/datum/object_window_info/obj_window = target.obj_window
 	obj_window.atoms_to_show = atoms_to_display
 	START_PROCESSING(SSobj_tab_items, obj_window)
@@ -210,6 +215,9 @@ SUBSYSTEM_DEF(statpanels)
 	// No turf? go away
 	if(!load_from.mob?.listed_turf)
 		return list()
+	// Lazy-init for the same lifecycle reasons as set_turf_examine_tab
+	if(!load_from.obj_window)
+		load_from.obj_window = new /datum/object_window_info(load_from)
 	var/datum/object_window_info/obj_window = load_from.obj_window
 	var/list/already_seen = obj_window.atoms_to_images
 	var/list/to_make = obj_window.atoms_to_imagify