Fix boltz-debug.sh output and add token caching

[bernd2022]

Summary

• Fix jq output logic that was silently failing for array results
• Add token caching (~58 min) to speed up repeated queries
• Cache file stored in /tmp with chmod 600 for security

Changes

Output fix: The script was receiving valid API responses but not displaying them because jq's error check (.message) failed on array results like [{"count":"1"}].

Token caching:

• First call authenticates and caches token to /tmp/lds-debug-token-<hash>.json
• Subsequent calls reuse cached token until ~58 min (before JWT expires at 60 min)
• Separate cache per DEBUG_ADDRESS using md5 hash

Test plan

• Verify simple queries return results
• Verify cache is used on subsequent calls
• Verify queries with WHERE clause work
• Verify invalid SQL returns proper error message