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/Models/SemanticMatchResult.cs

@@ -0,0 +1,33 @@
+namespace TrueCV.Application.Models;
+
+public record SemanticMatchResult
+{
+    public required string CandidateCompanyName { get; init; }
+    public required string CandidateCompanyNumber { get; init; }
+    public required int ConfidenceScore { get; init; }
+    public required string MatchType { get; init; } // Exact, TradingName, Subsidiary, Parent, NoMatch
+    public required string Reasoning { get; init; }
+    public bool IsMatch => ConfidenceScore >= 70;
+}
+
+public record CompanyMatchRequest
+{
+    public required string CVCompanyName { get; init; }
+    public required List<CompanyCandidate> Candidates { get; init; }
+}
+
+public record CompanyCandidate
+{
+    public required string CompanyName { get; init; }
+    public required string CompanyNumber { get; init; }
+    public string? CompanyStatus { get; init; }
+    public string? DateOfCreation { get; init; }
+}
+
+public record AIMatchResponse
+{
+    public required string BestMatchCompanyNumber { get; init; }
+    public required int ConfidenceScore { get; init; }
+    public required string MatchType { get; init; }
+    public required string Reasoning { get; init; }
+}