Strip astral-plane emojis from Tk button labels

Python 3.7's bundled Tcl/Tk on Windows is UCS-2 only and refuses
characters above U+FFFF. The button labels contained game-controller,
desktop, folder and refresh emojis (U+1F3AE, U+1F5A5, U+1F4C2, U+1F501),
so App.__init__ raised TclError and gui.main caught it, exited 1, and
the user saw 'nothing happened'.

Replace with plain Korean text. Per CLAUDE.md these emojis should not
have been added in the first place.

sephiria_inv/gui.py

@@ -409,11 +409,11 @@ class ScreenshotFrame(ttk.Frame):
 
         ctl = ttk.Frame(self)
         ctl.pack(fill="x")
-        ttk.Button(ctl, text="🎮 게임 창 선택…", command=self._pick_window).pack(side="left")
-        ttk.Button(ctl, text="🖥 전체 화면 캡처", command=self._capture_screen).pack(side="left", padx=4)
-        ttk.Button(ctl, text="📂 파일 열기…", command=self._open_file).pack(side="left", padx=4)
-        ttk.Button(ctl, text="🔁 영역 재지정", command=self._reselect_bbox).pack(side="left", padx=4)
-        ttk.Button(ctl, text="✅ 이 구성으로 계산", command=self._confirm).pack(side="right")
+        ttk.Button(ctl, text="게임 창 선택…", command=self._pick_window).pack(side="left")
+        ttk.Button(ctl, text="전체 화면 캡처", command=self._capture_screen).pack(side="left", padx=4)
+        ttk.Button(ctl, text="파일 열기…", command=self._open_file).pack(side="left", padx=4)
+        ttk.Button(ctl, text="영역 재지정", command=self._reselect_bbox).pack(side="left", padx=4)
+        ttk.Button(ctl, text="이 구성으로 계산", command=self._confirm).pack(side="right")
 
         self.status = ttk.Label(
             self,