feat(terminal): Align the terminal with IDEA's tabs, menu and settings

- ⌘T (Ctrl+Shift+T on Windows) opens a terminal tab while the terminal
  has focus; elsewhere the key keeps its IDE action.
- The tab bar's ▾ menu lists installed shells under "New Predefined
  Session" (login shell, shell integration) and links to Settings.
- Settings › Tools › Terminal: pick the shell path from the installed
  shells or browse for one, "Move focus to the Editor with Escape",
  fallback font, column width and a link to the Terminal keymap.

Claude-Session: https://claude.ai/code/session_01B65qLEKnkeYTGdbwhLpjCu

src/platform/keymaps/intellij-macos.ts

@@ -252,6 +252,8 @@ export const intellijMacos: Record<string, string[]> = {
   "db.sqlScript": [],
   "db.goToReferencedTable": [],
   "db.collapseAll": [],
+  // Terminal (keyWhen: terminalFocus); after VCS Update / Go to Test so it wins there.
+  "terminal.new": ["Meta+T"],
   // Last: later bindings win, so ⌘N is Generate in the editor and New in tool windows.
   "code.generate": ["Meta+N"],
 };

src/platform/keymaps/intellij-windows.ts

@@ -249,6 +249,8 @@ export const intellijWindows: Record<string, string[]> = {
   "db.sqlScript": [],
   "db.goToReferencedTable": [],
   "db.collapseAll": [],
+  // Terminal (keyWhen: terminalFocus); after VCS Update / Go to Test so it wins there.
+  "terminal.new": ["Ctrl+Shift+T"],
   // Last: later bindings win, so Alt+Insert is Generate in the editor and New in tool windows.
   "code.generate": ["Alt+Insert"],
 };

src/platform/keymaps/vscode-macos.ts

@@ -144,6 +144,7 @@ export const vscodeMacos: Record<string, string[]> = {
   "toolwindow.git": ["Ctrl+Shift+G"],
   "toolwindow.commit": [],
   "toolwindow.terminal": ["Ctrl+`"],
+  "terminal.new": [],
   "toolwindow.hideAll": ["Meta+B"],
   "toolwindow.maximize": [],
   "toolwindow.jumpToLast": [],