Add AI-powered company name matching using Claude API

Replace fuzzy string matching with semantic AI matching to fix false
positives where similar-sounding but different companies were matched
(e.g., "Families First CiC" incorrectly matching "FAMILIES AGAINST
CONFORMITY LTD").

Changes:
- Add ICompanyNameMatcherService interface and AICompanyNameMatcherService
  implementation using Claude Sonnet 4 for semantic company name comparison
- Add SemanticMatchResult and related models for AI match results
- Update CompanyVerifierService to use AI matching with fuzzy fallback
- Add detection for public sector employers, charities, and self-employed
  entries that cannot be verified via Companies House
- Update tests to work with new AI matcher integration

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/TrueCV.Application/Interfaces/ICompanyNameMatcherService.cs

@@ -0,0 +1,15 @@
+using TrueCV.Application.Models;
+
+namespace TrueCV.Application.Interfaces;
+
+public interface ICompanyNameMatcherService
+{
+    /// <summary>
+    /// Uses AI to semantically compare a company name from a CV against Companies House candidates.
+    /// Returns the best match with confidence score and reasoning.
+    /// </summary>
+    Task<SemanticMatchResult?> FindBestMatchAsync(
+        string cvCompanyName,
+        List<CompanyCandidate> candidates,
+        CancellationToken cancellationToken = default);
+}