🛡️ Sentinel: [SECURITY ENHANCEMENT] Add fetch timeouts to prevent DoS

[schmug]

🛡️ Sentinel: [SECURITY ENHANCEMENT] Add fetch timeouts to prevent DoS

🚨 Severity: ENHANCEMENT
💡 Vulnerability: Fetch calls did not have timeouts configured, which could lead to application hangs or client-side DoS if the upstream server is unresponsive.
🎯 Impact: An attacker or degraded network condition could exhaust client resources or cause server-side build scripts to hang indefinitely.
🔧 Fix: Added explicit signal: AbortSignal.timeout(10000) to global fetch calls in BlogApp.tsx, useProjects.ts, and github.ts. Also added comments explaining the security enhancement and recorded the learning in .jules/sentinel.md.
✅ Verification: Tested locally by verifying pnpm test, pnpm lint, and pnpm build pass successfully without regressions.

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PR created automatically by Jules for task 4959938185874236835 started by @schmug

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