fix caption dialog (#4799)

The Material 3 redesign seems to have broken the dialog when very small
images where used.
Also removes the weird background behind the context menu (seen in the
before screenshot)

Before / after:
<img
src="https://github.com/user-attachments/assets/c418125d-ef80-458f-9d94-fde428a2f59f"
width="280"/> <img
src="https://github.com/user-attachments/assets/b832b16d-0c18-4bf1-a263-de4fe0362854"
width="280"/>

app/src/main/java/com/keylesspalace/tusky/components/compose/dialog/CaptionDialog.kt

@@ -130,7 +130,7 @@ class CaptionDialog : DialogFragment() {
         dialog?.apply {
             window?.setLayout(
                 LinearLayout.LayoutParams.MATCH_PARENT,
-                LinearLayout.LayoutParams.MATCH_PARENT
+                LinearLayout.LayoutParams.WRAP_CONTENT
             )
             window?.setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE)
         }