feat(defects): read API — feed, per-section counts and history (T6)

GET /api/defects returns a newest-first feed joined to the project name,
bounded by limit; ?section=ID narrows to one section's history. GET
/api/defects/counts returns { sectionId: n } for the weak-point map. Adds a
(section_id, created_at) index and a db:seed script; ~2k rows query in ~20ms.

server/db/migrations/meta/_journal.json

@@ -15,6 +15,13 @@
       "when": 1779916898127,
       "tag": "0001_boring_randall",
       "breakpoints": true
+    },
+    {
+      "idx": 2,
+      "version": "7",
+      "when": 1779920052613,
+      "tag": "0002_mixed_chronomancer",
+      "breakpoints": true
     }
   ]
 }