Reject leading-zero semver values in local evaluation

[dmarticus]

Summary

Per semver 2.0.0 §2, numeric identifiers MUST NOT include leading zeros. Values like 1.07.3 or 01.2.3 are not valid semver — the local feature flag evaluator currently parses them silently (via intval("07") → 7), which means a person property of 1.07.3 would incorrectly match a semver_eq condition against 1.7.3.

This PR makes the parser reject leading zeros in numeric identifiers. Both override values and flag values are validated; invalid inputs throw InconclusiveMatchException so the condition simply does not match.

Matches the same fix applied to posthog-python #601 and posthog-go #200.

Changes

• parseSemver now uses a parseSemverNumeric helper that rejects strings with leading zeros (except literal "0").
• wildcardBounds uses the same helper, so 01.* and 1.07.* are rejected.
• Inverted the existing edge-case test testParseSemverLeadingZeros / testMatchPropertySemverLeadingZeros — they now assert rejection rather than acceptance.
• Added comprehensive coverage for override values, flag values, and all range operators (semver_gt, semver_caret, semver_tilde, semver_wildcard).

Test plan

• ./vendor/bin/phpunit --filter "Semver|parseSemver" test — 45 passed
• New rejection tests pass
• Literal 0 components still match (0.1.0, 1.0.0, 0.0.0)
• Full suite has no new regressions (one pre-existing unrelated failure: testLoadFeatureFlagsWrongKey)
• ./bin/fmt clean

[dmarticus]

Closing in favor of #147 — was based on a stale feature branch; recreated against main.