fix: fall back to vCard prePath in redactionFields and consolidate privacy phrase lists

- Extend `redactionFields(name, prePath?)` to parse the vCard property from an RFC 9537 `prePath` expression (e.g. `[?(@[0]=='email')]`) when the human-readable name alone doesn't identify fields; add `ADR_INDEX_FIELDS` to narrow a specific address element (`[3][N]`) to the right `ContactField`
- Pass `r.prePath` through in `extractContacts` so redactions with generic names (e.g. `"Redacted"`) still populate `redactedFields` correctly
- Split `PRIVACY_STRONG_KEYWORDS` source into `REDACTION_PHRASES` (text that stands in for a withheld value) and `PRIVACY_SERVICE_PHRASES` (proxy/shield names); derive `PLACEHOLDER_VALUE_PATTERNS` entries from `REDACTION_PHRASES` with `\b…\b` anchoring so the two lists can't drift apart
- Drop `!!registrant?.redacted` from the `privacyEnabled` check in `normalizeRdap`; `isPrivacyContact` and the RFC 9537 redaction scan already cover the same signal without double-counting
- Expand `isPlaceholderValue` test to assert that bare tokens (`"Unknown"`, `"Na"`) only match the whole value and not substrings like `"Unknown Pleasures Ltd"` or `"Na Health Inc"`
- Update `privacyEnabled` JSDoc to clarify it is a coarse signal (an email-only redaction can set it) and point callers to `redactedFields`/`privacyService` for precision

README.md

@@ -574,7 +574,7 @@ interface DomainRecord {
     >; // fields that were redacted (and are therefore absent)
     privacyService?: boolean; // name/organization is a privacy/proxy service (text kept), not a redaction notice
   }>;
-  privacyEnabled?: boolean; // registrant appears privacy-redacted based on name heuristics (privacy-service and redaction phrases) or RFC 9537 redactions
+  privacyEnabled?: boolean; // coarse: some registrant data was redacted or is behind a privacy service (name heuristics or RFC 9537 redactions); see the registrant contact's redactedFields/privacyService for which fields
   redactions?: Array<{
     name: string; // e.g. "Registrant Email"
     prePath?: string;