fix: pipeline content tracking + topic article preview

db_helper.py: save_article now calculates and persists word_count
generator.py: run_creator_blocking sets word_count for HTML-imported articles
writer.py: fix title regex stripping content-leading numbers (35岁后→岁后)
trends.py: fix Baidu hot_score str/int type comparison crash
database.py: add missing content_tasks.org_id ALTER TABLE migration
schemas.py + topics.py: topic list API returns article_count + articles[] previews
topics.html: table view and card view show article badges with word counts, clickable to open preview

Ultraworked with Sisyphus

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

.omo/run-continuation/ses_1dede8a7affeG6DxtfPUOviXrp.json

@@ -1,11 +1,10 @@
 {
   "sessionID": "ses_1dede8a7affeG6DxtfPUOviXrp",
-  "updatedAt": "2026-06-17T08:18:52.213Z",
+  "updatedAt": "2026-06-23T00:31:03.722Z",
   "sources": {
     "background-task": {
-      "state": "active",
-      "reason": "2 background task(s) active",
-      "updatedAt": "2026-06-17T08:18:52.213Z"
+      "state": "idle",
+      "updatedAt": "2026-06-23T00:31:03.722Z"
     }
   }
 }