fix: hardening round from code review (4 P1 + 15 P2)

P1:
- settingsStore: back up an unparseable settings.json to .bak before
  falling back to defaults, so the next mutation can no longer silently
  wipe custom themes/highlight rules
- ptyDispatcher: fan out per-session data/exit handlers (Set instead of
  a single slot) so SSH split panes stop stealing each other's stream
- FilePanel: monotonic refresh token keeps stale listings from painting
  over a newer navigation; upload finish no longer yanks the panel back
- settings.css: active settings-tab label derives from --chrome-fg so it
  stays visible on the shipped light themes

P2 (main/renderer):
- paste guard: a paste ending in a newline always confirms
- Workspace: closing an SSH pane no longer seeds the local cwd with a
  remote path
- tray: skip close-dialog continuation on a destroyed window
- commands: close zombie 'in-progress' session logs at hydrate
- zmodem: clear the stale offer timer before arming a new one
- connectionsStore: coerce/validate renderer input before persisting
- sftp: OperationError marker class keeps translated errors out of the
  transport-retry classifier
- CommandsPanel: surface save failures inside the dialog
- ConnectionSidebar: drop a tautological tooltip condition

P2 (i18n/tooling/tests):
- localize the 16 ANSI color labels and the highlight sample text
  (21 new keys across zh-CN/zh-TW/en/ja)
- sync-changelog: keep ### subheadings, normalize CRLF notes
- release.cjs: GitHub release reuse-by-tag (idempotent re-runs); fail
  loudly on a failed Gitea asset listing
- commands-store test: absent historyEnabled now truly tests absence

src/main/tray.ts

@@ -87,6 +87,9 @@ export function initTray(showOrCreate: () => void): void {
 }
 
 function hideToTray(win: BrowserWindow): void {
+  // A quit started while the close dialog was pending destroys the window
+  // before its resolution runs; touching a destroyed window throws.
+  if (win.isDestroyed()) return
   win.hide()
   if (process.platform === 'win32' && tray && !balloonShown) {
     balloonShown = true
@@ -126,6 +129,11 @@ export async function onMainWindowClose(win: BrowserWindow, e: Electron.Event, s
     checkboxChecked: false,
     noLink: true
   })
+  // The dialog resolves when the window is destroyed underneath it (tray exit
+  // or OS shutdown called app.quit() while it was open): the quit is already
+  // underway, so neither branch may run — and must not persist a choice the
+  // user never made.
+  if (win.isDestroyed()) return
   if (response === 0) {
     if (checkboxChecked) persistCloseAction('tray')
     hideToTray(win)