feat(cv-search-job): enrich diagnostics and add scan summary to results email

Add funnel-level logging to HtmlJobSearcher (total anchors found,
stage-1 href-filter count, stage-2 keyword-filter count) and warn
when the keyword list is empty. Log the full search URL and response
size to catch silent HTTP failures or bot-block pages.

In CvSearchJobTask, log keywords and active providers at session start,
per-provider URL counts after each scrape, and every scored URL with its
verdict (ACCEPTED / rejected) at Information level.

Add a scan summary block to the results email (both non-empty and
empty-results paths) showing the CV keywords used as chips and the
comma-separated list of providers scanned.

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

Jobs/cv-search-job/Tasks/CvSearchJobTask.cs

@@ -84,13 +84,35 @@ public sealed class CvSearchJobTask : IJobTask
 
         try
         {
-            var results = await RunSearchAsync(pending, db, cancellationToken);
+            var cvKeywords = pending.Keywords
+                .Split(',', StringSplitOptions.RemoveEmptyEntries)
+                .Select(k => k.Trim())
+                .Where(k => k.Length > 0)
+                .ToList();
+
+            var providers = GetProviders(pending.ProviderConfigJson);
+
+            _logger.LogInformation(
+                "Session {SessionId}: keywords=[{Keywords}] | providers=[{Providers}]",
+                pending.Id,
+                cvKeywords.Count > 0 ? string.Join(", ", cvKeywords) : "(none)",
+                providers.Count > 0 ? string.Join(", ", providers.Select(p => p.Name)) : "(none)");
+
+            var results = await RunSearchAsync(pending, cvKeywords, providers, db, cancellationToken);
 
             pending.Status = JobSearchStatus.Done;
             await db.SaveChangesAsync(cancellationToken);
 
             var attachmentFileName = BuildCvFileName(pending.CvDocumentId);
-            await _emailSender.SendResultsAsync(pending.Email, attachmentFileName, results, pending.Language, cancellationToken);
+            await _emailSender.SendResultsAsync(
+                pending.Email,
+                attachmentFileName,
+                results,
+                cvKeywords,
+                providers.Select(p => p.Name).ToList(),
+                pending.Language,
+                cancellationToken);
+
             _logger.LogInformation("Session {SessionId} done. {Count} results sent.", pending.Id, results.Count);
         }
         catch (Exception ex)
@@ -107,26 +129,27 @@ public sealed class CvSearchJobTask : IJobTask
     /// </summary>
     private async Task<List<JobSearchResultEntity>> RunSearchAsync(
         JobSearchSessionEntity session,
+        List<string> cvKeywords,
+        List<JobProviderConfig> providers,
         CvSearchDbContext db,
         CancellationToken ct)
     {
-        var cvKeywords = session.Keywords
-            .Split(',', StringSplitOptions.RemoveEmptyEntries)
-            .Select(k => k.Trim())
-            .Where(k => k.Length > 0)
-            .ToList();
+        if (cvKeywords.Count == 0)
+            _logger.LogWarning("Session {SessionId}: keyword list is empty — scraper will rely on provider InitialKeywords only", session.Id);
 
-        var providers = GetProviders(session.ProviderConfigJson);
         var jobUrls = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
 
         foreach (var provider in providers)
         {
             var urls = await _searcher.SearchJobUrlsAsync(provider, cvKeywords, ct);
+            _logger.LogInformation("Session {SessionId}: provider {Provider} returned {Count} URLs", session.Id, provider.Name, urls.Count);
             foreach (var url in urls) jobUrls.Add(url);
         }
 
         var candidates = jobUrls.Take(_settings.MaxJobsToMatch).ToList();
-        _logger.LogInformation("Session {SessionId}: {Count} candidate job URLs to match", session.Id, candidates.Count);
+        _logger.LogInformation(
+            "Session {SessionId}: {Total} unique URLs across all providers, scoring {Scoring} (cap={Cap})",
+            session.Id, jobUrls.Count, candidates.Count, _settings.MaxJobsToMatch);
 
         var results = new List<JobSearchResultEntity>();
 
@@ -143,11 +166,14 @@ public sealed class CvSearchJobTask : IJobTask
                 };
 
                 var matchResult = await _matcherApi.MatchJobAsync(matchRequest, ct);
+
+                _logger.LogInformation(
+                    "Session {SessionId}: {Url} → score={Score}% (threshold={Threshold}%) {Verdict}",
+                    session.Id, url, matchResult.Score, _settings.MinMatchScore,
+                    matchResult.Score >= _settings.MinMatchScore ? "ACCEPTED" : "rejected");
+
                 if (matchResult.Score < _settings.MinMatchScore)
-                {
-                    _logger.LogDebug("Session {SessionId}: {Url} scored {Score}% (below threshold)", session.Id, url, matchResult.Score);
                     continue;
-                }
 
                 var entity = new JobSearchResultEntity
                 {