Allow medications with only a generic name (no commercial name required) (#311)

* Initial plan

* feat: allow generic name only for medications (frontend changes)

- Add getMedDisplayName() helper for consistent name display
- Update validation to require either commercial or generic name
- Update all display locations to use display name fallback
- Add i18n keys for nameOrGenericRequired in en.json and de.json
- Remove required attribute from commercial name field
- Update FIELD_LIMITS.name.min from 1 to 0

Co-authored-by: DanielVolz <3275994+DanielVolz@users.noreply.github.com>

* feat: allow generic name only for medications (backend changes)

- Update Zod schema to allow empty name with cross-field refinement
- Update reminder scheduler to use name || genericName for display
- Update planner routes to match medications by display name
- Update existing tests to match new validation behavior

Co-authored-by: DanielVolz <3275994+DanielVolz@users.noreply.github.com>

* fix: update placeholder text and fix FIELD_LIMITS test

- Remove "(optional)" from generic name placeholder in en/de
- Update types.test.ts to expect FIELD_LIMITS.name.min = 0

Co-authored-by: DanielVolz <3275994+DanielVolz@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: DanielVolz <3275994+DanielVolz@users.noreply.github.com>

backend/src/services/reminder-scheduler.ts

@@ -353,7 +353,7 @@ async function getMedicationsNeedingReminder(
 
 		if (isCritical || isLow) {
 			lowStock.push({
-				name: row.name,
+				name: row.name || row.genericName || "",
 				medsLeft: currentPills,
 				daysLeft,
 				depletionDate,
@@ -379,7 +379,7 @@ async function getMedicationsNeedingPrescriptionReminder(userId: number): Promis
 				(row.prescriptionRemainingRefills ?? 0) <= (row.prescriptionLowRefillThreshold ?? 1)
 		)
 		.map((row) => ({
-			name: row.name,
+			name: row.name || row.genericName || "",
 			remainingRefills: row.prescriptionRemainingRefills ?? 0,
 			lowThreshold: row.prescriptionLowRefillThreshold ?? 1,
 			expiryDate: row.prescriptionExpiryDate ?? null,