[P2] Complete Vietnamese, Chinese, Arabic & Amharic policy translations (12 missing each)

[dmchaledev]

Context

Spanish policy coverage is now complete (62/62 bodies). The other four supported locales lag:

Locale	Policy bodies	Missing
es	62	0
vi	50	12
zh	50	12
ar	50	12
am	50	12

node scripts/translate/check-coverage.js reports these as warnings (English fallback is used), so visitors in these languages silently get English for the 12 newest policies — including the just-added Round-2 policies (P7–P11).

The work

• Run the translation pipeline (scripts/translate/) to generate the 12 missing policies-{vi,zh,ar,am}/*.md bodies + src/i18n/policy-meta-{vi,zh,ar,am}.json metadata entries.
• Review machine output (esp. Amharic) with native/fluent speakers before publishing — see scripts/translate/README.md.
• Get coverage to 62/62 across all five locales (warnings → clean).

Priority: Medium — multilingual reach is core to the platform's mission of serving Denver's immigrant communities.