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/cv-matcher-api.csproj

@@ -83,6 +83,5 @@
     <ProjectReference Include="..\cv-matcher-data\cv-matcher-data.csproj" />
     <ProjectReference Include="..\common\common.csproj" />
     <ProjectReference Include="..\..\Helpers\startup-helpers\startup-helpers.csproj" />
-    <ProjectReference Include="..\myai-data\myai-data.csproj" />
   </ItemGroup>
 </Project>