feat(intraday): add discovery and verification watch pipeline

scripts/testdata/intraday_discovery_llm_sample.json

@@ -0,0 +1,24 @@
+[
+  {
+    "event_type": "official_release",
+    "provider_name": "OpenAI",
+    "model_name": "GPT-5.6",
+    "provider_country": "US",
+    "title": "GPT-5.6 preview pricing update",
+    "summary": "OpenAI preview material indicates GPT-5.6 entered a preview pricing window.",
+    "candidate_urls": [
+      "https://openai.example.com/news/gpt-5-6-pricing"
+    ]
+  },
+  {
+    "event_type": "promo_campaign",
+    "provider_name": "DeepSeek",
+    "model_name": "DeepSeek-V4-Flash",
+    "provider_country": "CN",
+    "title": "DeepSeek V4 Flash campaign",
+    "summary": "Official campaign page shows a temporary promotional window for DeepSeek-V4-Flash.",
+    "candidate_urls": [
+      "https://deepseek.example.com/campaign/v4-flash"
+    ]
+  }
+]