fix: add timeout handling to registryValidation to prevent CLI hang

[TeapoyY]

When --registry-url points to an unreachable host, the CLI would hang indefinitely due to fetch() having no timeout.

Changes

• Adds AbortController with a 5-second timeout
• Uses clearTimeout to avoid memory leaks on successful fetch
• Provides a clear error message when timeout occurs
• Properly propagates the original error when fetch fails for other reasons

Testing

Tested manually with unreachable registry URL (blackholed IP):
\
asyncapi generate fromTemplate asyncapi.yaml @asyncapi/html-template --registry-url http://10.255.255.1
\
Expected: CLI fails fast with timeout error message
Before: CLI hangs indefinitely

Fixes #2027

[changeset-bot]

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Latest commit: bdc7dc7

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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

See analysis details on SonarQube Cloud

[aeworxet]

@TeapoyY, please read asyncapi/community#2295 (comment).

Note that #2039 is already assigned and participates in a mutex-like Bounty Program: pull requests from GitHub users other than the assigned Bounty Program Participant will not be reviewed.

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