fix(coach): keep updatedAt through storage-only rewrites

The title encryption backfill moved each Coach conversation's title into
ciphertext with a plain Prisma update, which stamps updatedAt. The Coach
panel orders and groups conversations by that column, so threads untouched
for months showed up under Today. The memory summary refresh did the same
in the background.

Storage-only rewrites now carry the row's own updatedAt and match on it, so
a turn that lands meanwhile wins and the row is retried on the next pass:
conversation titles, practitioner contacts, measurement and mood notes
(where updatedAt is the sync cursor), inventory notes, and the mood-note
script. The summary refresh writes through raw SQL. A guard freezes both
rules: every backfill write on a model with @updatedAt names the column or
is listed with the reason the stamp is wanted, and every conversation
write outside the person's own actions keeps it.

scripts/backfill-mood-note-column.ts

@@ -52,6 +52,7 @@ interface RowSnapshot {
   id: string;
   tags: string | null;
   note: string | null;
+  updatedAt: Date;
 }
 
 async function main(): Promise<void> {
@@ -74,7 +75,7 @@ async function main(): Promise<void> {
       tags: { not: null },
       note: null,
     },
-    select: { id: true, tags: true, note: true },
+    select: { id: true, tags: true, note: true, updatedAt: true },
   });
 
   console.log(`[backfill-note] scanned ${candidates.length} candidate rows`);
@@ -87,9 +88,11 @@ async function main(): Promise<void> {
 
     updated += 1;
     if (!dryRun) {
+      // The entry did not change for its reader; it keeps its `updatedAt`
+      // (the sync cursor) rather than taking the script's run time.
       await prisma.moodEntry.update({
         where: { id: row.id },
-        data: { note, tags: newTags },
+        data: { note, tags: newTags, updatedAt: row.updatedAt },
       });
     }
   }