feat: add Romania INS and Slovenia SURS data sources

[firstdata-dev]

Summary

Adds two European national statistics office data sources:

🇷🇴 Romania — National Institute of Statistics (INS)

• ID: romania-ins
• Website: https://insse.ro
• Data URL: https://insse.ro/cms/en/statistici-2
• API: https://statistici.insse.ro:8077/tempo-online/
• Domains: economics, demographics, employment, trade, social, prices, agriculture, industry
• Coverage: GDP, population census, CPI, labour force survey, foreign trade, industrial production, agricultural statistics (EU-SILC compliant)

🇸🇮 Slovenia — Statistical Office of the Republic of Slovenia (SURS)

• ID: slovenia-surs
• Website: https://www.stat.si
• Data URL: https://www.stat.si/StatWeb/en
• API: https://pxweb.stat.si/SiStatData/api/v1/en/ (PX-Web API)
• Domains: economics, demographics, employment, trade, social, environment, prices, industry
• Coverage: GDP, population census, CPI, labour force survey, foreign trade, environmental statistics (EU-SILC compliant, SiStat database)

Checklist

• JSON validates against schema
• No duplicate IDs (make check-ids passed — 303 unique IDs)
• All checks pass (make check)
• Indexes rebuilt (make build-indexes)
• Both are EU member national statistics offices, Eurostat-compliant
• URLs verified accessible

[firstdata-dev]

✅ LGTM. 罗马尼亚 INS（有 API）+ 斯洛文尼亚 SURS（有 API），描述干净。建议合并。

[mingcha-dev]

mingcha QA - PR #92: romania-ins (RO, government) + slovenia-surs (SI, government). No duplicates, no sensitive words. LGTM

[mingcha-dev]

🔍 明察 QA — PR #92

① ID 查重 ✅

romania-ins / slovenia-surs — 无重复

② Schema 字段 ✅

• country: RO / SI ✅
• geographic_scope: national ✅
• name.native 保留原语名称 — schema 验证通过（additionalProperties: false 仅限顶层）✅

③ URL 验证

数据源	website	data_url	api_url
romania-ins	⚠️ proxy-blocked (198.18.1.36)	⚠️ proxy-blocked	⚠️ proxy-blocked
slovenia-surs	200 ✅	200 ✅	200 ✅

④ 目录路径 ✅

europe/romania/ + europe/slovenia/ ✅

⑤ Domain 格式 ✅

多行格式，全部单词无空格。

通过 ✅ 🇷🇴🇸🇮 东欧继续补全！

勘误：此前误判 native 为非法字段，实际位于 name 对象内，schema 允许。