feat(job-search): read providers from DB and suppress link when none enabled

JobTokenService.CreateTokenAsync queries cvSearch.JobProviders for any
enabled row; returns null (no token created) when the table is empty or
all providers are disabled. TriggerStartAsync snapshots enabled providers
from DB at session-start time, preserving the existing snapshot contract.

CvMatcherController guards link-building on a non-null TokenId so the
"Start a job search" CTA is omitted from match emails when no providers
are configured.

JobSearchSettings.Providers list removed — provider config now lives
exclusively in the DB. CvSearchJobTask.GetProviders falls back to an
empty list with a warning (snapshot should always be populated from DB).

Closes #35

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

Apis/cv-matcher-api/Services/JobTokenService.cs

@@ -13,6 +13,9 @@ namespace Api.Services;
 
 /// <summary>
 /// Creates and validates one-time job search tokens, and creates the corresponding search sessions.
+/// Provider configuration is read from <c>cvSearch.JobProviders</c> at session-creation time and
+/// snapshotted into <c>JobSearchSessionEntity.ProviderConfigJson</c> so subsequent config changes
+/// do not affect already-queued sessions.
 /// </summary>
 public sealed class JobTokenService : IJobTokenService
 {
@@ -34,8 +37,15 @@ public sealed class JobTokenService : IJobTokenService
     }
 
     /// <inheritdoc />
-    public async Task<string> CreateTokenAsync(string cvDocumentId, string email, string language, CancellationToken ct)
+    public async Task<string?> CreateTokenAsync(string cvDocumentId, string email, string language, CancellationToken ct)
     {
+        var hasEnabledProviders = await _db.JobProviders.AnyAsync(p => p.Enabled, ct);
+        if (!hasEnabledProviders)
+        {
+            _logger.LogDebug("Job search token skipped — no enabled providers in cvSearch.JobProviders");
+            return null;
+        }
+
         var token = new JobSearchTokenEntity
         {
             Id = Guid.NewGuid().ToString("N"),
@@ -67,8 +77,13 @@ public sealed class JobTokenService : IJobTokenService
         var cv = await _rag.GetDocumentAsync(token.CvDocumentId, ct);
         var keywords = cv is not null ? ExtractKeywords(cv.Text) : string.Empty;
 
+        var enabledProviders = await _db.JobProviders
+            .Where(p => p.Enabled)
+            .OrderBy(p => p.DisplayOrder)
+            .ToListAsync(ct);
+
         var providerConfigJson = JsonSerializer.Serialize(
-            _settings.Providers.Where(p => p.Enabled).ToList(),
+            enabledProviders.Select(ToConfig).ToList(),
             new JsonSerializerOptions(JsonSerializerDefaults.Web));
 
         var session = new JobSearchSessionEntity
@@ -86,11 +101,41 @@ public sealed class JobTokenService : IJobTokenService
 
         _db.JobSearchSessions.Add(session);
         await _db.SaveChangesAsync(ct);
-        _logger.LogInformation("Job search session created. SessionId={SessionId}, Keywords={Keywords}", session.Id, keywords);
+        _logger.LogInformation(
+            "Job search session created. SessionId={SessionId}, Keywords={Keywords}, Providers={Providers}",
+            session.Id, keywords, string.Join(", ", enabledProviders.Select(p => p.Name)));
 
         return StartJobSearchStatus.Started;
     }
 
+    /// <summary>
+    /// Maps a <see cref="JobProviderEntity"/> to the <see cref="JobProviderConfig"/> DTO used by
+    /// <c>cv-search-job</c>. The <c>InitialKeywords</c> list is stored as a JSON array in the entity.
+    /// </summary>
+    private static JobProviderConfig ToConfig(JobProviderEntity entity)
+    {
+        List<string> keywords;
+        try
+        {
+            keywords = JsonSerializer.Deserialize<List<string>>(entity.InitialKeywordsJson,
+                new JsonSerializerOptions(JsonSerializerDefaults.Web)) ?? [];
+        }
+        catch
+        {
+            keywords = [];
+        }
+
+        return new JobProviderConfig
+        {
+            Name = entity.Name,
+            Enabled = entity.Enabled,
+            SearchUrlTemplate = entity.SearchUrlTemplate,
+            JobLinkContains = entity.JobLinkContains,
+            InitialKeywords = keywords,
+            MaxResults = entity.MaxResults
+        };
+    }
+
     /// <summary>
     /// Extracts up to 10 meaningful keywords from the CV text using simple heuristics (no LLM).
     /// Takes the first 5 usable lines, splits them into words, strips punctuation, and deduplicates.