refine(tui-v3): 行头/行尾跳转仅在首/末逻辑行触发

之前在任意逻辑行的视觉首/末行都会做"先跳行头/尾再跨行/进历史"的
两段式,中间行的两段式不直观。改成:中间逻辑行的视觉首/末行直接
做视觉上下移;只有第一逻辑行的视觉首行/最末逻辑行的视觉末行,才
触发"先跳到行头/尾,下次按键再进历史"。`_logical_visual_range`
因此变成死代码,顺手删掉。

frontends/tui_v3.py

@@ -2570,16 +2570,6 @@ class SB:
         total = self.buf.count('\n') + 1
         return line_no, total, ls, le
 
-    def _logical_visual_range(self, segs, line_no):
-        """返回第 line_no 个逻辑行在 segs 中的 (first_vi, last_vi)"""
-        lines = self.buf.split('\n')
-        iw = max(1, _term()[0] - 6)
-        first = 0
-        for i in range(line_no):
-            first += max(1, len(_wrap_cells(lines[i], iw)))
-        cnt = max(1, len(_wrap_cells(lines[line_no], iw)))
-        return first, first + cnt - 1
-
     def _cur_v(self, d: int) -> None:
         """↑/↓ roam by VISUAL row (a long single-line paste wraps to many rows
         yet stays one logical line — must still roam). At the top/bottom visual
@@ -5151,20 +5141,14 @@ class SB:
                     self._palette_sel = max(0, self._palette_sel - 1)
                 else:
                     self._sel = None
-                    line_no, total, ls, le = self._line_region()
                     segs = self._segs(max(1, _term()[0] - 6))
                     vi, _ = self._seg_at(segs)
-                    first_vi, _ = self._logical_visual_range(segs, line_no)
-                    if vi == first_vi:          # 在视觉首行
-                        if line_no == 0:
-                            if self.pos == ls:
-                                self._nav_hist(-1)
-                            else:
-                                self.pos = ls
-                        elif self.pos == ls:
-                            self._cur_v(-1)     # 已在行首 → 正常上移
+                    if vi == 0:                 # 视觉首行(必在第一逻辑行)
+                        _, _, ls, _ = self._line_region()
+                        if self.pos == ls:
+                            self._nav_hist(-1)
                         else:
-                            self.pos = ls       # 跳到该行行首
+                            self.pos = ls       # 先跳行首,下次再进历史
                     else:
                         self._cur_v(-1)
             elif o == 0x13:                       # Ctrl+S stash/restore draft
@@ -5175,20 +5159,14 @@ class SB:
                     self._palette_sel = min(n - 1, self._palette_sel + 1) if n else 0
                 else:
                     self._sel = None
-                    line_no, total, ls, le = self._line_region()
                     segs = self._segs(max(1, _term()[0] - 6))
                     vi, _ = self._seg_at(segs)
-                    first_vi, last_vi = self._logical_visual_range(segs, line_no)
-                    if vi == last_vi:           # 在视觉末行
-                        if line_no == total - 1:
-                            if self.pos == le:
-                                self._nav_hist(1)
-                            else:
-                                self.pos = le
-                        elif self.pos == le:
-                            self._cur_v(1)      # 已在行末 → 正常下移
+                    if vi == len(segs) - 1:     # 视觉末行(必在最末逻辑行)
+                        _, _, _, le = self._line_region()
+                        if self.pos == le:
+                            self._nav_hist(1)
                         else:
-                            self.pos = le       # 跳到该行行末
+                            self.pos = le       # 先跳行尾,下次再进历史
                     else:
                         self._cur_v(1)
             elif o == 0x02:                       # ← caret left