Add weighted directory subscriptions

[jt55401]

Summary

• evaluate multiple weighted trust-directory subscriptions through canonical signer reputation routes
• preserve the legacy trustScore response during migration while preferring score
• harden directory fetches with protocol, redirect, credential, timeout, and response handling
• pin canonicalization 760593d4a02e9fffa56dc4d002eb52ab2ade1b49
• document install, standalone use, and the subscription contract

Validation

• npm test: 57 tests
• npm run build
• npm run typecheck
• npm pack --dry-run
• git diff --check