feat(v3.7.0): add timeline and advanced diffing system

- introduce TimelineView for historical snapshots
- allow comparison between any two snapshots
- implement DiffService for structured domain diffs
- improve diff visualization with clear change indicators
- add navigation across changes
- optimize history loading for performance
- extend CLI and export to support timeline data

1 files changed, 8 insertions, 0 deletions

diff --git a/LookupSnapshot.swift b/LookupSnapshot.swift
index a817805..752e7f2 100644
--- a/LookupSnapshot.swift
+++ b/LookupSnapshot.swift
@@ -20,6 +20,10 @@ struct LookupSnapshot {
     let isPartialSnapshot: Bool
     let validationIssues: [String]
     let totalLookupDurationMs: Int?
+    let snapshotIndex: Int?
+    let previousSnapshotID: UUID?
+    let changeCount: Int
+    let severitySummary: ChangeSeverity?
     let dnsSections: [DNSSection]
     let dnsError: String?
     let availabilityResult: DomainAvailabilityResult?
@@ -90,6 +94,10 @@ extension HistoryEntry {
             isPartialSnapshot: isPartialSnapshot,
             validationIssues: validationIssues,
             totalLookupDurationMs: totalLookupDurationMs,
+            snapshotIndex: snapshotIndex,
+            previousSnapshotID: previousSnapshotID,
+            changeCount: changeCount,
+            severitySummary: severitySummary,
             dnsSections: dnsSections,
             dnsError: nil,
             availabilityResult: availabilityResult,