#21473 fix(cloud): compose Run through authenticated VM endpoints

Use internal fetches to the existing authenticated VM, exec, and delete endpoints instead of invoking route handlers inside another Next request context. This keeps the existing auth, entitlement, Freestyle, and cleanup lifecycle while avoiding nested request-context failures in staging.

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Summary by cubic

Composes Cloud Run through the existing authenticated VM, exec, and delete endpoints instead of invoking route handlers directly in a nested Next request context.

• Uses fetch against the internal VM API for provisioning, execution, and cleanup.
• Preserves the existing auth, entitlement, Freestyle, and cleanup lifecycle.
• Avoids nested request-context failures seen in staging.

Summary by CodeRabbit

• Maintenance
  • Updated internal handling of run provisioning, command execution, and cleanup. Existing user-facing workflows remain unchanged.
• User Impact
  • No new features or visible behavior changes are included in this release.