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/routes/medications.ts

@@ -42,7 +42,7 @@ const medicationStartDateSchema = z
 
 const medicationSchema = z
 	.object({
-		name: z.string().trim().min(1).max(100),
+		name: z.string().trim().max(100).default(""),
 		genericName: z.string().trim().max(100).nullable().optional(),
 		takenBy: z.array(z.string().trim().max(100)).default([]), // Medication-level takenBy (fallback)
 		packageType: packageTypeSchema,
@@ -66,6 +66,10 @@ const medicationSchema = z
 		intakes: z.array(intakeSchema).min(1).max(12).optional(),
 		blisters: z.array(blisterSchema).min(1).max(12).optional(), // Legacy format
 	})
+	.refine(
+		(data) => (data.name && data.name.length > 0) || (data.genericName && data.genericName.length > 0),
+		{ message: "Either 'name' or 'genericName' must be provided", path: ["name"] }
+	)
 	.refine((data) => data.intakes || data.blisters, { message: "Either 'intakes' or 'blisters' must be provided" })
 	.refine(
 		(data) => {