SHA3-03 FIPS 202 conformance harness for bit-level examples

[turkananation]

SHA3-03 FIPS 202 Conformance Harness for Bit-Level Examples

Summary

Add a FIPS 202 conformance harness for official byte and non-byte-aligned NIST
examples.

Scope

• Add a small internal BitString helper for tests.
• Normalize NIST examples into a runner-friendly format.
• Test 0, 5, 30, 1600, 1605, and 1630-bit message examples.
• Test SHAKE truncation / non-byte output samples or document the exact
  unsupported boundary.

Acceptance criteria

• Public byte APIs are tested against byte-aligned examples.
• Non-byte examples are either tested through an internal harness or
  explicitly documented as out of public API scope.
• Broad FIPS 202 wording is blocked until this issue is resolved.

References

• doc/FIPS202_SP800185_RELEASE_GUIDE.md - Bit-String and Non-Byte Input Policy
• FIPS 202 Appendix B
• NIST example values page

Priority: P0