[Fix] Tuple::compare use strcmp instead of spaceship operator (#53)

[s2x]

Summary

Fixes #53.

Replace the spaceship operator ($packed1 <=> $packed2) with strcmp($packed1, $packed2) <=> 0 for byte-wise comparison of packed tuple data. PHP's <=> can coerce numeric-looking strings (numeric-string coercion), which is a latent correctness footgun. strcmp() compares byte-by-byte and the result is normalized to -1/0/1.

Changes

• src/Tuple/Tuple.php:125 — Changed return $packed1 <=> $packed2 to return strcmp($packed1, $packed2) <=> 0
• tests/Unit/Tuple/TupleCompareTest.php — Added compareNumericLookingStrings() test that verifies correct ordering of bytes that look like numeric strings, plus equality and regular string ordering

Verification

• All 318 unit tests pass (including all 45 tuple comparison tests)
• Code style (PHPCS) passes
• No new PHPStan errors

Acceptance Criteria

• Unit test(s) added covering ordering of values whose packed form is numeric-looking, plus general ordering
• Functional test(s) covered by existing tuple-ordering tests (all pass)
• Changelog entry — no CHANGELOG file exists in the project