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/cv-matcher-api/Services/JobTextExtractor.cs

@@ -6,6 +6,10 @@ using Microsoft.Extensions.Options;
 
 namespace Api.Services;
 
+/// <summary>
+/// Extracts normalised plain text from a job posting, either from a pasted description or by
+/// fetching and stripping the HTML of the job page URL.
+/// </summary>
 public sealed class JobTextExtractor : IJobTextExtractor
 {
     private readonly HttpClient _http;
@@ -19,6 +23,7 @@ public sealed class JobTextExtractor : IJobTextExtractor
         _http.DefaultRequestHeaders.UserAgent.ParseAdd("MyAi.ro CV Matcher/1.0");
     }
 
+    /// <inheritdoc />
     public async Task<string> ExtractAsync(string? jobUrl, string? jobDescription, CancellationToken ct)
     {
         var pasted = Normalize(jobDescription ?? string.Empty);
@@ -37,12 +42,14 @@ public sealed class JobTextExtractor : IJobTextExtractor
         return Limit(Normalize(WebUtility.HtmlDecode(html)));
     }
 
+    /// <summary>Truncates text to the configured maximum character count.</summary>
     private string Limit(string value)
     {
         var max = Math.Max(4000, _settings.MaxJobTextChars);
         return value.Length <= max ? value : value[..max];
     }
 
+    /// <summary>Collapses all whitespace runs to single spaces and trims the result.</summary>
     private static string Normalize(string value)
     {
         if (string.IsNullOrWhiteSpace(value)) return string.Empty;