Add XML doc to all service interfaces and implementations (#26)

- Update CLAUDE.md: replace incorrect 'no XML doc on internal code' rule
  with the correct convention (XML doc on all public methods and
  non-trivial private/protected helpers)
- Restore /// <summary> on FileDownloadController private helpers
  (HandleRangeRequest, StreamRangeAsync)
- Add full XML doc to all service contracts:
  ICaptchaVerifier, IEmailSender, ICvMatcherService, IJobTextExtractor,
  IJobTokenService, IDocumentClassifier, IRagService, ITextChunker,
  ITextExtractor, IEmailTemplateService, ITemplateService
- Add /// <summary> and /// <inheritdoc /> to all concrete service classes
  and their methods: RecaptchaVerifier, EmailApiEmailSender,
  SmtpEmailDispatcher, CvMatcherService, JobTextExtractor, JobTokenService,
  RagService, DocumentClassifier, TextChunker, TextExtractor,
  HtmlJobSearcher, CvSearchEmailSender, CvSearchJobTask,
  EmailTemplateService, DbTemplateService

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

Apis/email-api/Services/SmtpEmailDispatcher.cs

@@ -8,6 +8,10 @@ using Models.Settings;
 
 namespace EmailApi.Services;
 
+/// <summary>
+/// Wraps an HTML body fragment in the branded HTML shell and sends the resulting email via SMTP using MailKit.
+/// Attaches files from the shared file-storage volume when an attachment path is provided.
+/// </summary>
 public sealed class SmtpEmailDispatcher
 {
     private readonly SmtpSettings _smtp;
@@ -29,6 +33,13 @@ public sealed class SmtpEmailDispatcher
         _environmentName = Environment.GetEnvironmentVariable("APP_ENVIRONMENT_NAME") ?? "Development";
     }
 
+    /// <summary>
+    /// Builds a <see cref="MimeMessage"/> from <paramref name="req"/>, wraps the body in the HTML shell,
+    /// optionally attaches a file, and sends via the configured SMTP server.
+    /// Logs a warning and returns without throwing when the SMTP host is not configured.
+    /// </summary>
+    /// <param name="req">Email payload containing recipients, subject, HTML body, and optional attachment path.</param>
+    /// <param name="ct">Cancellation token.</param>
     public async Task SendAsync(SendEmailRequest req, CancellationToken ct)
     {
         if (string.IsNullOrWhiteSpace(_smtp.Host))