feat(medications): validate per-dose dose windows on schedule writes

Accept an optional doseWindows array on the schedule create/update routes:
each entry pins an explicit on-time range [start,end] to one of the
schedule's times-of-day, defaulting to the symmetric grace band when
absent. Reject malformed ranges (bad HH:mm, a timeOfDay outside the
schedule, an inverted span) with a 422 so the persisted window can never
feed the band minter a degenerate range.

Regenerates the OpenAPI contract for the additive field (iOS-safe).

src/app/api/medications/[id]/route.ts

@@ -318,6 +318,10 @@ export const PUT = apiHandler(
               ...(s.cyclicOffWeeks !== undefined && {
                 cyclicOffWeeks: s.cyclicOffWeeks,
               }),
+              // v1.15.18 — per-dose configurable on-time windows. A `schedules`
+              // replace re-creates the rows, so the column is re-written each
+              // time; absent leaves it NULL (default ±1h derivation).
+              ...(s.doseWindows !== undefined && { doseWindows: s.doseWindows }),
             };
           }),
         },

src/app/api/medications/route.ts

@@ -326,6 +326,10 @@ export const POST = apiHandler(async (request: NextRequest) => {
             ...(s.cyclicOffWeeks !== undefined && {
               cyclicOffWeeks: s.cyclicOffWeeks,
             }),
+            // v1.15.18 — per-dose configurable on-time windows. Stored as the
+            // validated `{ timeOfDay, start, end }[]` JSON; absent leaves the
+            // column NULL (every slot on the default ±1h derivation).
+            ...(s.doseWindows !== undefined && { doseWindows: s.doseWindows }),
           };
         }),
       },