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>

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

backend/package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "medassist-ng-backend",
-  "version": "1.15.1",
+  "version": "1.16.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "medassist-ng-backend",
-      "version": "1.15.1",
+      "version": "1.16.0",
       "dependencies": {
         "@fastify/cookie": "^11.0.2",
         "@fastify/cors": "^11.2.0",