fix: filter analysis_summary in JS instead of Prisma WHERE clause

Prisma 5 rejects both null and Prisma.DbNull as WHERE filter values for
Json? fields (no clean IS NOT NULL operator). Filter the result array in
JS after the query — the output is immediately cached so this only runs
once per cache period.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/routes/experiments.js

@@ -1,6 +1,5 @@
 const router = require('express').Router();
 const { body } = require('express-validator');
-const { Prisma } = require('@prisma/client');
 const prisma = require('../lib/prisma');
 const cache = require('../lib/cache');
 const auditMiddleware = require('../middleware/auditMiddleware');
@@ -373,11 +372,8 @@ router.get('/:id/daily-statuses', async (req, res, next) => {
       const next = new Date(d); next.setUTCDate(next.getUTCDate() + 1);
       where.date = { gte: d, lt: next };
     }
-    if (analysisOnly) {
-      where.NOT = { analysis_summary: Prisma.DbNull };
-    }
 
-    const statuses = await prisma.dailyStatus.findMany({
+    let statuses = await prisma.dailyStatus.findMany({
       where,
       select: {
         id: true,
@@ -393,6 +389,12 @@ router.get('/:id/daily-statuses', async (req, res, next) => {
       orderBy: { date: 'asc' },
     });
 
+    // Prisma 5 has no clean IS NOT NULL filter for Json? fields; filter in JS.
+    // The result is cached so this only runs once per cache period.
+    if (analysisOnly) {
+      statuses = statuses.filter((s) => s.analysis_summary !== null);
+    }
+
     cache.set(cacheKey, statuses);
     res.json(statuses);
   } catch (err) { next(err); }