Add Copilot instructions for repository conventions and architecture

[Copilot]

Configures GitHub Copilot coding agent instructions per best practices.

Changes

• Created .github/copilot-instructions.md with:
  • Technology stack (Java 25, Spring Boot 3.5.7, Maven, H2, Thymeleaf, HTMX, Bt torrent library)
  • Package structure organized by feature/domain
  • Coding conventions: Lombok patterns (@RequiredArgsConstructor, @Slf4j), constructor injection with final fields
  • Naming patterns: *Controller, *Service, *Repository, *DTO
  • Spring Boot specifics: @Controller vs @RestController, GenerationType.IDENTITY, async/scheduling patterns
  • Build commands, configuration details, external API integrations (YTS, YouTube)
  • Reference to docs/tasks.md for architectural improvement backlog

Example Convention

@Controller
@RequiredArgsConstructor
public class WebController {
    final UserPreferences userPreferences;
    final WatchList watchList;
    
    @GetMapping("/")
    public String index(Model model) {
        // Controller logic
    }
}

Copilot will now provide context-aware suggestions aligned with the project's established patterns.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>✨ Set up Copilot instructions</issue_title>
<issue_description>Configure instructions for this repository as documented in Best practices for Copilot coding agent in your repository.

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes ✨ Set up Copilot instructions #123

---

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[Brogrammer1912]

Looks good to me

[Copilot]

Pull request overview

This PR adds comprehensive GitHub Copilot instructions to help the AI coding agent provide context-aware suggestions aligned with the StreamSpace project's established patterns and conventions.

• Creates .github/copilot-instructions.md documenting technology stack, architecture, and coding standards
• Establishes clear conventions for dependency injection, naming patterns, and Spring Boot usage
• Provides reference documentation for external integrations and build processes

[Copilot]

The URL should use "http" instead of "https" for localhost:8080. Standard Spring Boot applications run on HTTP by default unless SSL is explicitly configured.

Suggested change

	- Web UI: https://localhost:8080/
	- Web UI: http://localhost:8080/