FL-1110 feat: add pos/phone E.164 normalizer (NormalizeE164) + PII-redaction reflection guard

• new package sdk/pos/phone: shared E.164 canonicalization for FL-1078 phone-based linkage (D-49/D-51); dependency-free, table-driven tests
• sevenrooms: add reflection guard test asserting rawEntity carries no new PII-named field (defense-in-depth for D-33/D-48)

Closes FL-1110