fix(weekly): localize zh-TW watch copy

[atomchung]

Refs #683

User before / after

Before, a zh-TW WeeklyMarketRead used Traditional-Chinese headings and analysis but inserted the English _watch() check and trigger into 下週關注. After, the default/skip path and every offered focus render the watch and trigger fully in Traditional Chinese.

Scope

• localize presentation in render_zh_tw() only;
• keep the domain packet, trigger (too_heavy × positive frozen VIX delta), read-only lifecycle, provider behavior and persistence unchanged;
• add a dedicated locale regression suite covering every focus for zh-TW and zh-CN;
• add a real zh-TW prepare → preview → weekly-market-read → --focus trajectory.

No L1 lookup, memory, scheduler, threshold, card, schema, state or #676 change.

Evidence expected

• focused locale suite;
• existing weekly-market suite;
• full offline suite on Python 3.11 and 3.12 through PR CI.

Owner explicitly authorized merge after green CI in the current session.