Add PII masking with --show-pii flag (#14)

[C0MPL3XDEV]

Summary

• Add PII masking module that redacts email, phone, IP, and hostname in structured output
• Output is masked by default; use --show-pii flag to reveal raw data
• Applied to all CLI commands that support --output

Files changed

• eagleosint/masking.py — new module with mask functions and regex patterns
• eagleosint/output.py — integrated masking into write_results()
• eagleosint/cli.py — added --show-pii flag to all output commands
• tests/test_masking.py — 23 tests

Test plan

• All 146 tests pass
• JSON/CSV output masked by default
• --show-pii reveals unmasked data
• Email, phone, IP, hostname masking verified