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, 6 deletions

diff --git a/DomainDig/WatchlistView.swift b/DomainDig/WatchlistView.swift
index 5670e5e..389ae91 100644
--- a/DomainDig/WatchlistView.swift
+++ b/DomainDig/WatchlistView.swift
@@ -169,13 +169,13 @@ struct WatchlistView: View {
                                 shareTrackedDomains(format: .pdf)
                             }
                         } else {
-                            Button("CSV Export • Available in Pro") {}
+                            Button("CSV Export • Available in Pro") { /* Inert: disabled Pro upsell affordance. */ }
                                 .disabled(true)
-                            Button("JSON Export • Available in Pro") {}
+                            Button("JSON Export • Available in Pro") { /* Inert: disabled Pro upsell affordance. */ }
                                 .disabled(true)
-                            Button("Markdown Export • Available in Pro") {}
+                            Button("Markdown Export • Available in Pro") { /* Inert: disabled Pro upsell affordance. */ }
                                 .disabled(true)
-                            Button("PDF Export • Available in Pro") {}
+                            Button("PDF Export • Available in Pro") { /* Inert: disabled Pro upsell affordance. */ }
                                 .disabled(true)
                         }
                     } label: {
@@ -250,7 +250,7 @@ struct WatchlistView: View {
             Button("Save") {
                 viewModel.saveCurrentWatchlistView(name: newSavedViewName)
             }
-            Button("Cancel", role: .cancel) {}
+            Button("Cancel", role: .cancel) { /* Dismiss only; SwiftUI closes the alert. */ }
         } message: {
             Text("Saves the current tag, filter, and sort as a reusable preset.")
         }
@@ -736,7 +736,7 @@ struct TrackedDomainDetailView: View {
                     viewModel.rerunInspection(for: liveTrackedDomain, useSnapshotResolver: true)
                 }
             }
-            Button("Cancel", role: .cancel) {}
+            Button("Cancel", role: .cancel) { /* Dismiss only; SwiftUI closes the alert. */ }
         } message: {
             Text(viewModel.resolverMismatchNote(for: liveTrackedDomain) ?? "Choose how to reproduce the most recent snapshot.")
         }