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

tests/commands-store.mjs

@@ -144,10 +144,13 @@ writeSettings({ historyLimit: 50, historyEnabled: true })
 store.recordCommand('recorded-again')
 ok(store.listHistory()[0].command === 'recorded-again', 'historyEnabled=true resumes recording')
 
-// Default (keys absent from settings.json) records, matching a fresh install.
-writeSettings({})
-store.recordCommand('default-on')
-ok(store.listHistory()[0].command === 'default-on', 'absent switch defaults to recording')
+// Default (key absent from settings.json): the shipped default is recording OFF
+// (DEFAULT_SETTINGS.terminal.historyEnabled = false, gate is `=== true`), and a
+// fresh install has no key at all. The writeSettings helper always injects
+// `historyEnabled: true`, so the absence case writes the file directly.
+writeFileSync(join(userData, 'settings.json'), JSON.stringify({ terminal: {}, system: {} }), 'utf8')
+store.recordCommand('default-off')
+ok(!store.listHistory().some((h) => h.command === 'default-off'), 'absent switch defaults to NOT recording (shipped default)')
 store.clearHistory()
 
 // ---- 4. Library CRUD + ordering ------------------------------------------------