feat(cv-matcher): add AiPrompts table; remove MyAiDbContext dependency

cv-matcher-data:
- Add AiPromptEntity (Key, Language, Value, Description, UpdatedAt)
- Add AiPrompts DbSet to CvMatcherDbContext with composite PK
- Migration AddAiPrompts: create cvMatcher.AiPrompts table and seed
  ai.cv-match.system-prompt (language "*") with the current prompt value

cv-matcher-api:
- Add IAiPromptsRepository / EfAiPromptsRepository under Data/Repositories/
- CvMatcherService: inject IAiPromptsRepository; replace _templates.Render(...)
  with async DB lookup + simple string replacement
- Program.cs: register IAiPromptsRepository (scoped); remove MyAiDbContext,
  ITemplateService/DbTemplateService registrations and MyAiDbContext migration call
- Remove myai-data ProjectReference

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

Apis/cv-matcher-api/Data/Repositories/EfAiPromptsRepository.cs

@@ -0,0 +1,24 @@
+using CvMatcher.Data;
+using CvMatcher.Data.Repositories.Contracts;
+using Microsoft.EntityFrameworkCore;
+
+namespace CvMatcher.Data.Repositories;
+
+public sealed class EfAiPromptsRepository : IAiPromptsRepository
+{
+    private readonly CvMatcherDbContext _db;
+
+    public EfAiPromptsRepository(CvMatcherDbContext db)
+    {
+        _db = db;
+    }
+
+    public async Task<string?> GetAsync(string key, string language, CancellationToken ct)
+    {
+        return await _db.AiPrompts
+            .AsNoTracking()
+            .Where(x => x.Key == key && x.Language == language)
+            .Select(x => x.Value)
+            .FirstOrDefaultAsync(ct);
+    }
+}