Fix job search: location filtering, keyword quality, anchor filter bypass

Closes #41

- Add RequireKeywordInAnchor per-provider flag (default true); set false for
  ejobs.ro and bestjobs.eu so Stage 2 anchor-text filter is skipped — their
  search URL already filters by relevance server-side
- Update AI system prompts (en + ro) to extract concise job-board-friendly
  keywords (role title + key tech, not abstract concepts) and candidate location
- Propagate location through JobMatchResponse -> CreateJobSearchTokenRequest ->
  JobSearchTokenEntity -> JobSearchSessionEntity
- Add {location} and {location-slug} substitution in HtmlJobSearcher
- Update provider SearchUrlTemplates to include location:
    ejobs.ro:    /locuri-de-munca/{location-slug}?q={keywords}
    bestjobs.eu: /ro/locuri-de-munca-in-{location-slug}?keywords={keywords}
    linkedin.com: ?keywords={keywords}&location={location}
- Three new migrations: AddRequireKeywordInAnchorAndLocation,
  ImproveKeywordsAndAddLocation, AddLocationToProviders

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

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

@@ -34,7 +34,7 @@ public sealed class JobTokenService : IJobTokenService
     }
 
     /// <inheritdoc />
-    public async Task<string?> CreateTokenAsync(string cvDocumentId, string email, string language, IReadOnlyList<string> keywords, CancellationToken ct)
+    public async Task<string?> CreateTokenAsync(string cvDocumentId, string email, string language, IReadOnlyList<string> keywords, string? location, CancellationToken ct)
     {
         var hasEnabledProviders = await _db.JobProviders.AnyAsync(p => p.Enabled, ct);
         if (!hasEnabledProviders)
@@ -50,6 +50,7 @@ public sealed class JobTokenService : IJobTokenService
             Email = email,
             Language = language,
             Keywords = string.Join(",", keywords),
+            Location = location,
             ExpiresAt = DateTime.UtcNow.AddDays(_settings.TokenExpiryDays),
             Used = false,
             CreatedAt = DateTime.UtcNow
@@ -57,7 +58,7 @@ public sealed class JobTokenService : IJobTokenService
 
         _db.JobSearchTokens.Add(token);
         await _db.SaveChangesAsync(ct);
-        _logger.LogInformation("Job search token created. TokenId={TokenId}, CvDocumentId={CvDocumentId}, Keywords={Keywords}", token.Id, cvDocumentId, token.Keywords);
+        _logger.LogInformation("Job search token created. TokenId={TokenId}, CvDocumentId={CvDocumentId}, Keywords={Keywords}, Location={Location}", token.Id, cvDocumentId, token.Keywords, token.Location);
         return token.Id;
     }
 
@@ -92,6 +93,7 @@ public sealed class JobTokenService : IJobTokenService
             Language = token.Language,
             Status = JobSearchStatus.Pending,
             Keywords = keywords,
+            Location = token.Location,
             ProviderConfigJson = providerConfigJson,
             CreatedAt = DateTime.UtcNow
         };
@@ -126,7 +128,8 @@ public sealed class JobTokenService : IJobTokenService
             JobLinkContains = entity.JobLinkContains,
             InitialKeywords = keywords,
             MaxResults = entity.MaxResults,
-            UseHeadlessBrowser = entity.UseHeadlessBrowser
+            UseHeadlessBrowser = entity.UseHeadlessBrowser,
+            RequireKeywordInAnchor = entity.RequireKeywordInAnchor
         };
     }