i18n: align search-scope wording (en + zh_CN)

[YRWoods]

Summary

Align three incomplete search-scope strings with the rest of the UI (tabs, history, bookmarks, top sites) in both en and zh_CN.

Rationale

• overlay_searchPlaceholder / popup_searchSources / options_heroDesc already list all four sources
• cmd_search, notify_installedBody, and popup_searchTabsBookmarks still said only tabs/bookmarks

Changes

Key	Change
cmd_search	Include history + top sites
notify_installedBody	Same scope; \\$ / \\$ placeholders unchanged
popup_searchTabsBookmarks	Full source list label

How I tested

• Same message keys in both locale files
• Placeholder defs still match for notify_installedBody
• node --test tests/*.test.js — all pass

Fixes #14

[TuYv]

Thanks for auditing the English and Simplified Chinese search-scope strings. There is one blocking placeholder regression to fix before this can merge:

• In both locale files, notify_installedBody changes $search$ and $batch$ to \\$. Pounce's formatter only replaces named $name$ tokens, so the installed notification now renders literal \$ instead of the keyboard shortcuts. Please restore the named tokens and add a focused regression test that formats this message with both shortcut substitutions.

Please also keep the diff focused by reverting the unrelated overlay_tabCount formatting-only change, settle on consistent Chinese terminology for history/top sites, and manually verify that the longer popup label fits in both locales.

[YRWoods]

Addressed review:

1. Restored named $search$ / $batch$ tokens in notify_installedBody (en + zh_CN).
2. Regression test formats installed body with both shortcuts.
3. Reverted unrelated overlay_tabCount formatting-only change.
4. Search-scope wording still expanded (tabs/history/bookmarks/top sites) in both locales.

Please re-review.

[YRWoods]

Ready for re-review: named $search$ / $batch$ restored + regression test; overlay_tabCount formatting noise removed.

[YRWoods]

Withdrawing.