feat: multi-language interface (zh-CN/zh-TW/en/ja), multilingual offline changelog, settings robustness

i18n
- shared/i18n: dependency-free t() with flat per-namespace dictionaries
  (common/settings/workspace/terminal/ssh/panels/main), zh-CN fallback
- language picker in Settings -> System; antd ConfigProvider locale follows it
- main process tracks the language too: tray menu, close prompt, ssh/sftp/
  zmodem errors and the log TUI marker are translated; tray rebuilds on change

changelog
- CHANGELOG.md (zh-CN canonical) + .zh-TW/.en/.ja, bundled via ?raw and read
  per interface language with per-version fallback to zh-CN (no network)
- sync-changelog.cjs merges RELEASE_NOTES[.<lang>].md per release; release.cjs
  refuses to publish without a zh-CN entry for the version

settings robustness
- closeAction 'ask' survives the sanitizer (was silently coerced to 'tray',
  which made the 'ask every time' option dead)
- highlight rules are repaired instead of dropped: string priority, 0/1
  enabled, missing fg colour; unknown fields preserved
- load-time warnings are written to settings-warnings.log (deduped, capped)

terminal/UI
- configurable terminal toolbar: open working directory (default on), session
  log recording (off), open logs folder (off)
- global shortcut field records key combos (modifier or F-key required)
- input suggestions + command history default to off, with a one-time reset
  migration for existing installs
- settings dialog scrolling fixed (antd v6 renamed the tabs container), theme
  gallery nested scrollbar removed, joined segmented pickers with readable
  selected-state text

tests: settings-store.mjs (15 checks) added; commands-store.mjs updated for
the new off-by-default history setting

tests/settings-store.mjs

@@ -0,0 +1,115 @@
+/**
+ * Settings-store self-test (settings-store.mjs).
+ *
+ * Guards the sanitizer's repair-instead-of-drop behavior:
+ *   - closeAction 'ask' survives a save/load round trip (it used to be coerced
+ *     to 'tray', which made the "ask every time" option dead in the UI)
+ *   - a rule with a repairable shape (priority "5", enabled 1, missing fg
+ *     colour) is corrected rather than dropped
+ *   - an unusable entry is skipped and written to settings-warnings.log
+ *
+ * Build + run:
+ *   npx esbuild src/main/settingsStore.ts --bundle --platform=node --format=cjs \
+ *     --outfile=tests/.settings-store.cjs --alias:electron=./tests/electron-stub.cjs \
+ *     --alias:@shared=./src/shared
+ *   node tests/settings-store.mjs
+ */
+import { mkdtempSync, readFileSync, existsSync, writeFileSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { createRequire } from 'node:module'
+
+const require = createRequire(import.meta.url)
+const userData = mkdtempSync(join(tmpdir(), 'ot-settings-'))
+process.env.OT_STUB_USERDATA = userData
+
+const store = require('./.settings-store.cjs')
+
+let failed = 0
+const ok = (cond, msg) => {
+  console.log(`  ${cond ? 'ok' : 'FAIL'}: ${msg}`)
+  if (!cond) failed++
+}
+
+const rule = (over = {}) => ({
+  id: 'r1',
+  pattern: '\\bERROR\\b',
+  enabled: true,
+  priority: 5,
+  color: { fg: '#ff0000' },
+  note: 'note',
+  ...over
+})
+
+const roundTrip = async (patch) => {
+  const current = store.loadSettings()
+  await store.saveSettings({ ...current, ...patch })
+  return store.loadSettings()
+}
+
+// ---- 1. closeAction enum ----------------------------------------------------
+console.log('[closeAction]')
+for (const action of ['tray', 'exit', 'ask']) {
+  const back = (await roundTrip({ system: { ...store.loadSettings().system, closeAction: action } })).system.closeAction
+  ok(back === action, `closeAction '${action}' survives the round trip (got '${back}')`)
+}
+{
+  const back = (await roundTrip({ system: { ...store.loadSettings().system, closeAction: 'nonsense' } })).system.closeAction
+  ok(back === 'tray', `unknown closeAction falls back to 'tray' (got '${back}')`)
+}
+
+// ---- 2. highlight-rule repair ----------------------------------------------
+console.log('[highlight rules]')
+{
+  const out = (await roundTrip({ highlightRules: [rule()] })).highlightRules
+  ok(out.length === 1 && out[0].priority === 5 && out[0].color.fg === '#ff0000', 'well-formed rule is untouched')
+}
+{
+  const out = (await roundTrip({ highlightRules: [rule({ priority: '5' })] })).highlightRules
+  ok(out.length === 1 && out[0].priority === 5, `priority "5" repaired to a number (got ${out.length} rule(s))`)
+}
+{
+  const out = (await roundTrip({ highlightRules: [rule({ enabled: 1 })] })).highlightRules
+  ok(out.length === 1 && out[0].enabled === true, 'enabled 1 repaired to true')
+}
+{
+  const out = (await roundTrip({ highlightRules: [rule({ color: { bg: '#333333' } })] })).highlightRules
+  ok(out.length === 1 && typeof out[0].color.fg === 'string' && out[0].color.bg === '#333333', 'missing fg gets a default colour, bg kept')
+}
+{
+  const out = (await roundTrip({ highlightRules: [rule({ priority: 500 })] })).highlightRules
+  ok(out.length === 1 && out[0].priority === 100, 'out-of-range priority is clamped')
+}
+{
+  const out = (await roundTrip({ highlightRules: [rule({ note: 42, extraField: 'kept' })] })).highlightRules
+  ok(out.length === 1 && out[0].note === undefined && out[0].extraField === 'kept', 'non-string note dropped, unknown fields preserved')
+}
+{
+  const out = (await roundTrip({ highlightRules: [rule(), rule({ id: undefined })] })).highlightRules
+  ok(out.length === 1, 'unusable entry skipped, valid one kept')
+}
+{
+  const out = (await roundTrip({ highlightRules: [] })).highlightRules
+  ok(out.length === 0, 'an explicitly empty rule list stays empty')
+}
+
+// ---- 3. warnings land in a log file ----------------------------------------
+console.log('[warnings log]')
+{
+  writeFileSync(
+    join(userData, 'settings.json'),
+    JSON.stringify({ terminal: { fontSize: '16' }, highlightRules: [rule({ priority: 'x' })] }),
+    'utf8'
+  )
+  store.loadSettings()
+  const file = join(userData, 'settings-warnings.log')
+  const text = existsSync(file) ? readFileSync(file, 'utf8') : ''
+  ok(text.includes('terminal.fontSize'), 'terminal key type mismatch is logged')
+  ok(text.includes('priority repaired'), 'rule repair is logged')
+  const size = text.length
+  store.loadSettings()
+  ok(readFileSync(file, 'utf8').length === size, 'identical warnings are not appended twice')
+}
+
+console.log(failed === 0 ? '\n[settings] ALL CHECKS PASSED' : `\n[settings] ${failed} CHECK(S) FAILED`)
+process.exit(failed === 0 ? 0 : 1)