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, 7 insertions, 3 deletions

diff --git a/DomainDig/IntegrationService.swift b/DomainDig/IntegrationService.swift
index 23085d3..de24c23 100644
--- a/DomainDig/IntegrationService.swift
+++ b/DomainDig/IntegrationService.swift
@@ -768,9 +768,7 @@ private final class SMTPChannel {
             connection.stateUpdateHandler = { [weak self] state in
                 switch state {
                 case .ready:
-                    DispatchQueue.global(qos: .utility).async {
-                        self?.startReceiveLoop()
-                    }
+                    self?.scheduleReceiveLoop()
                     continuation.resume()
                 case .failed(let error):
                     continuation.resume(throwing: error)
@@ -782,6 +780,12 @@ private final class SMTPChannel {
         }
     }
 
+    private func scheduleReceiveLoop() {
+        DispatchQueue.global(qos: .utility).async { [weak self] in
+            self?.startReceiveLoop()
+        }
+    }
+
     func cancel() {
         connection.cancel()
     }