[Search Git Status] use box drawing chars for staged/unstaged header

functions/_fzf_report_diff_type.fish

@@ -1,16 +1,18 @@
 # helper for _fzf_preview_changed_file
 # prints out something like
-# +--------+
-# | Staged |
-# +--------+
+# ╭────────╮
+# │ Staged │
+# ╰────────╯
 function _fzf_report_diff_type --argument-names diff_type --description "Print a distinct colored header meant to preface a git patch."
     # number of "-" to draw is the length of the string to box + 2 for padding
     set repeat_count (math 2 + (string length $diff_type))
-    set horizontal_border +(string repeat --count $repeat_count -)+
+    set line (string repeat --count $repeat_count ─)
+    set top_border ╭$line╮
+    set btm_border ╰$line╯
 
     set_color yellow
-    echo $horizontal_border
-    echo "| $diff_type |"
-    echo $horizontal_border
+    echo $top_border
+    echo "│ $diff_type │"
+    echo $btm_border
     set_color normal
 end