fix(security): harden verifier command execution

[Canvinus]

Summary

• Replace verifier near and Git shell-string calls with argument-based execFile(..., shell: false).
• Validate networkId, NEAR account IDs, GitHub source snapshot URLs, and pinned 40-character commit SHAs before executing verifier commands.
• Ensure temporary clone folders are cleaned up on IPFS/pinning failures.
• Apply non-breaking npm audit lockfile updates.

Validation

• npm test -- --runInBand
• npm run build
• npm run lint
• git diff --check
• npm audit --omit=dev now only reports the known low-severity near-api-js/elliptic chain requiring a semver-major near-api-js@7.2.0 migration.