fix: add timeout to registry URL validation to prevent CLI hang

[md-amer]

Summary

Fixes #2027

The CLI hangs indefinitely when --registry-url points to an unreachable host (e.g., http://10.255.255.1) because registryValidation() calls fetch() with no timeout or AbortController.

Changes

• Added AbortController with a 5-second timeout to the fetch call in registryValidation()
• Switched from GET to HEAD for a lighter validation request (we only need to check reachability, not download the response body)
• Added a clear timeout-specific error message: Registry URL timed out after 5s: <url>
• Cleanup: clearTimeout in a finally block to prevent timer leaks

Before

$ asyncapi generate fromTemplate asyncapi.yaml @asyncapi/html-template --registry-url http://10.255.255.1
# CLI hangs forever

After

$ asyncapi generate fromTemplate asyncapi.yaml @asyncapi/html-template --registry-url http://10.255.255.1
# Error: Registry URL timed out after 5s: http://10.255.255.1
# (exits cleanly in ~5 seconds)

Test plan

• Added unit tests for registryURLParser() — validates URL format handling
• Added unit tests for registryValidation() — confirms timeout behavior with unreachable host
• All 7 new tests passing
• All existing unit tests unaffected

🤖 Generated with Claude Code

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[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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