test: expand PII redaction coverage

[slegarraga]

Locks down current redaction behavior beyond the single happy path.

• Multiple emails in one string are all redacted.
• International phone formats are redacted.
• Short extension-only digit runs remain unchanged.
• Two known over-match cases are documented in assertions: ext 12 attached to a phone is redacted together, and a long non-phone digit run is conservatively redacted.
• Text without PII passes through unchanged.

Verified with Vitest, ESLint, and TypeScript.

Closes #19

[royalpinto007]

Closing this one. The author is no longer active on these repos, so it cannot be iterated on, and @BabuBahir has been building a fuller version of this same test file on #19 that also documents two real over-match cases and surfaced a genuine bug (#47).

Nothing wrong with the code here, it is just better to land the more complete version in one go.