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, 9 insertions, 5 deletions

diff --git a/DomainDig/Models.swift b/DomainDig/Models.swift
index 6989cba..d83dc79 100644
--- a/DomainDig/Models.swift
+++ b/DomainDig/Models.swift
@@ -244,8 +244,14 @@ struct DomainChangeSummary: Codable, Equatable {
         changedSections = try container.decodeIfPresent([String].self, forKey: .changedSections) ?? []
         generatedAt = try container.decode(Date.self, forKey: .generatedAt)
         severity = try container.decodeIfPresent(ChangeSeverity.self, forKey: .severity) ?? (hasChanges ? .medium : .low)
+        let defaultImpact: ChangeImpactClassification
+        if severity == .high {
+            defaultImpact = .critical
+        } else {
+            defaultImpact = hasChanges ? .warning : .informational
+        }
         impactClassification = try container.decodeIfPresent(ChangeImpactClassification.self, forKey: .impactClassification)
-            ?? (severity == .high ? .critical : (hasChanges ? .warning : .informational))
+            ?? defaultImpact
         message = try container.decodeIfPresent(String.self, forKey: .message)
             ?? (changedSections.isEmpty ? "No meaningful changes" : changedSections.joined(separator: " • "))
         observedFacts = try container.decodeIfPresent([String].self, forKey: .observedFacts) ?? []
@@ -562,12 +568,10 @@ enum DomainClassificationKind: String, Codable, CaseIterable, Sendable {
     case unknown
 
     var title: String {
-        switch self {
-        case .staticSite:
+        if self == .staticSite {
             return "Static"
-        default:
-            return rawValue.capitalized
         }
+        return rawValue.capitalized
     }
 }