feat(backup): carry per-schedule units-per-dose through backup and restore

The schedule exporter enumerates columns, so the new per-schedule
units-per-dose needs adding by hand: export it as a Decimal string in
the disaster-recovery payload, accept it in the wire schema, and write
it back on restore (NULL stays NULL to inherit). Extend the round-trip
test to prove a half-tablet slot survives export and re-import.

src/app/api/admin/backups/[id]/restore/route.ts

@@ -581,6 +581,9 @@ const handler = apiHandler(
                     windowEnd: s.windowEnd,
                     label: s.label ?? null,
                     dose: s.dose ?? null,
+                    // #219 — per-schedule units per dose. Prisma coerces the
+                    // Decimal string; NULL / absent stays NULL (inherit).
+                    unitsPerDose: s.unitsPerDose ?? null,
                     daysOfWeek: s.daysOfWeek ?? null,
                     timesOfDay: s.timesOfDay ?? [],
                     reminderGraceMinutes: s.reminderGraceMinutes ?? null,

src/lib/export/__tests__/full-backup-payload.test.ts

@@ -131,6 +131,8 @@ function makePrisma() {
               scheduleType: "CYCLIC",
               cyclicOnWeeks: 3,
               cyclicOffWeeks: 1,
+              // #219 — per-schedule units per dose (a half tablet at this slot).
+              unitsPerDose: { toString: () => "0.5000" },
               doseWindows: [
                 { timeOfDay: "08:00", start: "07:30", end: "09:00" },
               ],
@@ -502,6 +504,8 @@ describe("buildFullBackupPayload disaster-recovery mode", () => {
               scheduleType: "CYCLIC",
               cyclicOnWeeks: 3,
               cyclicOffWeeks: 1,
+              // #219 — Decimal → string, round-tripped through the DR payload.
+              unitsPerDose: "0.5000",
             }),
           ],
         }),

src/lib/export/full-backup-payload.ts

@@ -507,6 +507,10 @@ export async function buildFullBackupPayload(
               cyclicOnWeeks: s.cyclicOnWeeks,
               cyclicOffWeeks: s.cyclicOffWeeks,
               doseWindows: s.doseWindows,
+              // #219 — per-schedule units per dose. Decimal → string like the
+              // medication-level column; NULL (inherit) stays NULL.
+              unitsPerDose:
+                s.unitsPerDose == null ? null : s.unitsPerDose.toString(),
             }
           : {}),
         windowStart: s.windowStart,

src/lib/validations/backup.ts

@@ -127,6 +127,9 @@ const medicationScheduleSchema = z
     windowEnd: z.string().min(1),
     label: z.string().nullable().optional(),
     dose: z.string().nullable().optional(),
+    // #219 — per-schedule units per dose. Serialised as a Decimal string in a
+    // DR file (or a number in a hand-authored one); NULL means inherit.
+    unitsPerDose: z.union([z.string(), z.number()]).nullable().optional(),
     daysOfWeek: z.string().nullable().optional(),
     timesOfDay: z.array(z.string()).optional(),
     reminderGraceMinutes: z.number().int().nullable().optional(),