PR 6: Database migration validation - fresh/upgrade test complete

✅ Database Setup:
- Created PostgreSQL kartselldb with kartsell user
- SSH port forward established (localhost:5432 → 178.104.200.7:5432)

✅ DbMigrator Fixes:
- Fixed migration path discovery (AppContext.BaseDirectory fallback)
- Added empty variable dictionary to suppress DbUp preprocessing
- Fixed PostgreSQL dollar quoting conflict ($policy$ → $$)

✅ Migration Results:
- All 21 migrations executed successfully
- Schema versions journal created and tracked
- 21 scripts processed in order, no rollback needed

Status: FRESH DATABASE DEPLOYMENT SUCCESSFUL
- kartselldb fully initialized with v16 schema
- Ready for application startup

Next: Deploy application and run integration tests

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

frontend/src/shared/ui/adapter/compatibility.js

@@ -0,0 +1,29 @@
+const componentByCapability = {
+    'button': 'Button', 'text-field': 'TextField', 'text-area': 'TextArea', 'select': 'Select',
+    'multi-select': 'MultiSelect', 'checkbox': 'Checkbox', 'date-field': 'DateField',
+    'number-field': 'NumberField', 'dialog': 'Dialog', 'status-tag': 'StatusTag',
+    'inline-message': 'InlineMessage', 'paginator': 'Paginator', 'tabs': 'Tabs', 'data-grid': 'DataGrid'
+};
+export function evaluateUiAdapterCompatibility(adapter, requiredCapabilities, requireProductionEligible = false) {
+    const issues = [];
+    if (adapter.descriptor.contractVersion !== '4.0') {
+        issues.push({ code: 'CONTRACT_VERSION', severity: 'ERROR', detail: `Expected 4.0, got ${adapter.descriptor.contractVersion}` });
+    }
+    for (const capability of requiredCapabilities) {
+        if (!adapter.descriptor.capabilities.has(capability)) {
+            issues.push({ code: 'MISSING_CAPABILITY', severity: 'ERROR', detail: capability });
+            continue;
+        }
+        const component = adapter.components[componentByCapability[capability]];
+        if (!component)
+            issues.push({ code: 'MISSING_COMPONENT', severity: 'ERROR', detail: capability });
+    }
+    if (requireProductionEligible && !adapter.descriptor.productionEligible) {
+        issues.push({ code: 'PRODUCTION_INELIGIBLE', severity: 'ERROR', detail: adapter.descriptor.id });
+    }
+    return { adapterId: adapter.descriptor.id, contractVersion: adapter.descriptor.contractVersion, compatible: !issues.some(x => x.severity === 'ERROR'), issues };
+}
+export function assertUiAdapterCompatibility(report) {
+    if (!report.compatible)
+        throw new Error(`UI adapter ${report.adapterId} is incompatible: ${report.issues.map(x => `${x.code}:${x.detail}`).join(', ')}`);
+}