feat: insurance section — overview, documents, analysis, KVG premium comparison

- Insurance overview page (/insurance): current policies table with type,
  provider, premium, franchise, coverage, and document links
- Documents page: upload and manage insurance documents
- Analysis page: coverage gap analysis per insurance type
- Priminfo integration (/insurance/priminfo): KVG premium comparison by
  insurer, model (TAR/HMO/etc.), franchise level, and accident coverage
  via embedded Priminfo iframe (no public API available)
- Backend: Insurance, PraemienEntry, PraemienPolice models with migrations
- Sidebar: insurance nav group with flyout and dropdown
- i18n: all keys in DE/EN/FR/IT

backend/finance/migrations/0023_add_praemien_police.py

@@ -0,0 +1,34 @@
+# Generated by Django 6.0.4 on 2026-05-24 11:38
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('finance', '0022_add_praemien_entry'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='PraemienPolice',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('versicherer_id', models.PositiveIntegerField(db_index=True)),
+                ('kanton', models.CharField(max_length=2)),
+                ('region', models.PositiveSmallIntegerField()),
+                ('altersklasse', models.CharField(max_length=10)),
+                ('unfalleinschluss', models.CharField(max_length=10)),
+                ('tariftyp', models.CharField(max_length=10)),
+                ('tarifbezeichnung', models.CharField(max_length=200)),
+                ('franchisestufe', models.CharField(max_length=10)),
+                ('franchise_chf', models.PositiveSmallIntegerField()),
+                ('praemie', models.DecimalField(decimal_places=2, max_digits=8)),
+                ('data_year', models.PositiveSmallIntegerField(db_index=True)),
+            ],
+            options={
+                'indexes': [models.Index(fields=['kanton', 'region', 'altersklasse', 'unfalleinschluss', 'tariftyp', 'franchisestufe', 'data_year'], name='finance_pra_kanton_e430cb_idx')],
+                'unique_together': {('versicherer_id', 'kanton', 'region', 'altersklasse', 'unfalleinschluss', 'tariftyp', 'franchisestufe', 'data_year')},
+            },
+        ),
+    ]