v4.8.3: Clear SonarCloud new-code issues

Fixes the 4 reported bugs and ~97 code smells flagged in the new-code
period. No behavior changes.

Bugs (swift:S3923) — DomainInspectionService's confidenceFor* helpers each
returned `error == nil ? .low : .low`, an inert conditional. Simplified to
`return .low` and dropped the now-unused `error` parameter.

Smells:
- Merged 14 identical `.empty`/`.error` switch branches in DomainViewModel
- Consolidated duplicate implementations (clearPresentedResults/reset,
  String.nonEmpty/nilIfEmpty, ExportFormat.id/fileExtension)
- Extracted nested ternaries into TLSGrade.tone, EmailSecurityGrade.tone,
  and ChangeImpactClassification.color; removed ContentView.impactColor
  and the duplicate mapping in BatchResultsView
- Documented empty closures and singleton inits
- Marked unused protocol-conformance parameters `_`
- Renamed CloudSyncTrigger.`import` to `imported` (raw value preserved)
  and SSLSessionDelegate's _serverTrust/_tlsMetadata
- Merged nested ifs in the DER parser; flattened closure nesting in
  PortScanService and IntegrationService
- Replaced two-case switches with if/else

Left open: S107 (init parameter counts), S115 (constants mirroring DoH and
ipapi JSON keys), S1075 (false positives on https:// literals), and two
S117 hits on SwiftUI $binding shorthand. These want a Won't Fix resolution
in SonarCloud, not a code change.

1 files changed, 6 insertions, 7 deletions

diff --git a/DomainDig/LocalNotificationService.swift b/DomainDig/LocalNotificationService.swift
index d3474e3..3648cb8 100644
--- a/DomainDig/LocalNotificationService.swift
+++ b/DomainDig/LocalNotificationService.swift
@@ -5,7 +5,7 @@ import UserNotifications
 final class LocalNotificationService {
     static let shared = LocalNotificationService()
 
-    private init() {}
+    private init() { /* Singleton; use the shared instance. */ }
 
     static let domainUserInfoKey = "domain"
     static let domainCategoryIdentifier = "domain-event"
@@ -188,14 +188,14 @@ private final class NotificationCenterDelegate: NSObject, UNUserNotificationCent
     static let shared = NotificationCenterDelegate()
 
     func userNotificationCenter(
-        _ center: UNUserNotificationCenter,
-        willPresent notification: UNNotification
+        _: UNUserNotificationCenter,
+        willPresent _: UNNotification
     ) async -> UNNotificationPresentationOptions {
         [.banner, .list, .sound]
     }
 
     func userNotificationCenter(
-        _ center: UNUserNotificationCenter,
+        _: UNUserNotificationCenter,
         didReceive response: UNNotificationResponse
     ) async {
         let userInfo = response.notification.request.content.userInfo
@@ -204,10 +204,9 @@ private final class NotificationCenterDelegate: NSObject, UNUserNotificationCent
         else { return }
 
         let action: DomainDigDeepLink.Action
-        switch response.actionIdentifier {
-        case LocalNotificationService.reinspectActionIdentifier:
+        if response.actionIdentifier == LocalNotificationService.reinspectActionIdentifier {
             action = .inspect(domain)
-        default:
+        } else {
             // Default tap: open the tracked domain's detail.
             action = .detail(domain)
         }