feat(news): seed 14 tech/AI news sources (8 countries)

briefing/digest 의 cross-country tech 토픽 다양성 확보용 source seed.
- KR ×2: GeekNews (Hada), AI Times
- US ×4: Hacker News, ArsTechnica AI, The Verge Tech, TechCrunch
- GB ×2: The Register, BBC Technology
- DE ×1: Heise Online
- JP ×2: ITmedia News, Gigazine
- CN ×1: 36Kr
- FR ×1: ZDNet France
- IN ×1: Analytics India Magazine

idempotent: WHERE NOT EXISTS (name). 운영 DB 에는 이미 적용됨,
백업 복원/신규 deploy 환경에서 자동 시드.

수집 검증 (2026-05-13 1차 fire, 8 source):
- 성공: Hacker News 30 / ArsTechnica AI 20 / Verge 10 / TC 20 / Register 50 / Heise 153 (총 283건 신규)
- 후속 fix: GeekNews 의 http redirect → feedburner 직접 URL, AI Times URL 오타 → S1N1.xml.

content category 는 news_sources.category (Tech / AI) 로 보존, briefing 의 country
필터 (MIN_COUNTRIES_PER_TOPIC ≥ 2) 와 호환.

migrations/262_seed_tech_ai_news_sources.sql

@@ -0,0 +1,26 @@
+-- 2026-05-13 — 기술/AI 뉴스 source seed (14건, 8개국)
+-- WHERE NOT EXISTS 로 idempotent. 기존 row 보존, 신규만 insert.
+-- briefing/digest 의 cross-country tech 토픽 cluster 다양성 확보.
+-- 8 country: CN, DE, FR, GB, IN, JP, KR, US. category = Tech / AI.
+
+INSERT INTO news_sources (name, country, language, feed_type, feed_url, category, enabled)
+SELECT v.name, v.country, v.language, v.feed_type, v.feed_url, v.category, v.enabled
+FROM (VALUES
+    ('GeekNews (Hada)',          'KR', 'ko', 'rss', 'https://feeds.feedburner.com/geeknews-feed',                'Tech', true),
+    ('AI Times',                 'KR', 'ko', 'rss', 'https://www.aitimes.com/rss/S1N1.xml',                      'AI',   true),
+    ('Hacker News',              'US', 'en', 'rss', 'https://hnrss.org/frontpage?count=30',                      'Tech', true),
+    ('ArsTechnica AI',           'US', 'en', 'rss', 'https://arstechnica.com/ai/feed/',                          'AI',   true),
+    ('The Verge Tech',           'US', 'en', 'rss', 'https://www.theverge.com/rss/index.xml',                    'Tech', true),
+    ('TechCrunch',               'US', 'en', 'rss', 'https://techcrunch.com/feed/',                              'Tech', true),
+    ('The Register',             'GB', 'en', 'rss', 'https://www.theregister.com/headlines.atom',                'Tech', true),
+    ('Heise Online',             'DE', 'de', 'rss', 'https://www.heise.de/rss/heise-atom.xml',                   'Tech', true),
+    ('ITmedia News',             'JP', 'ja', 'rss', 'https://rss.itmedia.co.jp/rss/2.0/aiplus.xml',              'AI',   true),
+    ('Gigazine',                 'JP', 'ja', 'rss', 'https://gigazine.net/news/rss_2.0/',                        'Tech', true),
+    ('36Kr',                     'CN', 'zh', 'rss', 'https://36kr.com/feed',                                     'Tech', true),
+    ('Numerama',                 'FR', 'fr', 'rss', 'https://www.numerama.com/feed',                             'Tech', true),
+    ('YourStory',                'IN', 'en', 'rss', 'https://yourstory.com/feed',                                   'Tech', true),
+    ('BBC Technology',           'GB', 'en', 'rss', 'https://feeds.bbci.co.uk/news/technology/rss.xml',          'Tech', true)
+) AS v(name, country, language, feed_type, feed_url, category, enabled)
+WHERE NOT EXISTS (
+    SELECT 1 FROM news_sources ns WHERE ns.name = v.name
+);