refactor(terminal): unify terminal selection using global settings

- Remove terminal selector from Session Manager page
- Backend now reads terminal preference from global settings
- Add terminal name mapping (iterm2 → iterm) for compatibility
- Add WezTerm support to macOS terminal options
- Add WezTerm translations for zh/en/ja

src/i18n/locales/en.json

@@ -300,7 +300,8 @@
           "iterm2": "iTerm2",
           "alacritty": "Alacritty",
           "kitty": "Kitty",
-          "ghostty": "Ghostty"
+          "ghostty": "Ghostty",
+          "wezterm": "WezTerm"
         },
         "windows": {
           "cmd": "Command Prompt",

src/i18n/locales/ja.json

@@ -300,7 +300,8 @@
           "iterm2": "iTerm2",
           "alacritty": "Alacritty",
           "kitty": "Kitty",
-          "ghostty": "Ghostty"
+          "ghostty": "Ghostty",
+          "wezterm": "WezTerm"
         },
         "windows": {
           "cmd": "コマンドプロンプト",

src/i18n/locales/zh.json

@@ -300,7 +300,8 @@
           "iterm2": "iTerm2",
           "alacritty": "Alacritty",
           "kitty": "Kitty",
-          "ghostty": "Ghostty"
+          "ghostty": "Ghostty",
+          "wezterm": "WezTerm"
         },
         "windows": {
           "cmd": "命令提示符",