Add Email and ClientIpAddress audit fields to cvSearch.JobSearchSessions and JobSearchResults

Captures client IP at job-search link-click time and threads it through to the session.
Both Email and ClientIpAddress are copied from session to each result row during processing.
Closes #47

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Apis/cv-matcher-api-models/Requests/StartJobSearchRequest.cs

@@ -0,0 +1,11 @@
+namespace CvMatcher.Models.Requests;
+
+/// <summary>
+/// Request body sent by <c>api</c> when activating a one-time job-search link.
+/// Carries the caller's IP address so it can be persisted on the session for auditing.
+/// </summary>
+public sealed class StartJobSearchRequest
+{
+    /// <summary>Client IP address forwarded by the api layer. Null when not available.</summary>
+    public string? ClientIpAddress { get; set; }
+}