feat(patients): fix date bug, convenio dropdown, redesign grupo familiar

- Fix dataNascimento date format error: convert dd/MM/yyyy → yyyy-MM-dd when
  loading EditarPacienteModal so <input type="date"> validates correctly
- Change convênio field from free text to dropdown populated from planos table
- Redesign grupo familiar: search a patient as family member instead of named
  group, with parentesco field (datalist with common options, accepts custom)
- GET /api/pacientes: proper camelCase aliases, LEFT JOINs for grupoFamiliarNome
  and indicadoPorNome, sort parameter support (az/za/convenio/recentes)
- Add startup migrations: ADD COLUMN IF NOT EXISTS for grupofamiliarid,
  grupofamiliarrelacao, indicadorporid on pacientes table
- savePaciente: preserve caller-supplied id instead of overwriting with Math.random
- Add grupoFamiliarRelacao to Paciente type

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/services/backend.ts

@@ -220,7 +220,7 @@ export const HybridBackend = {
 
   savePaciente: async (paciente: Partial<Paciente>) => {
     const data = enforceUppercase(paciente);
-    const body = { ...data, id: Math.random().toString() };
+    const body = { ...data, id: data.id || `p_${Date.now()}` };
     const res = await apiFetch(`${API_URL}/pacientes`, {
       method: 'POST',
       headers: { 'Content-Type': 'application/json' },