Raise ArgumentError for unsupported EoTime comparison operands

[OskarEichler]

Summary

Instantiate the intended ArgumentError when an unsupported comparison operand lacks to_f. Calling ArgumentError as a method currently raises NoMethodError instead, hiding the intended diagnostic.

Reproduction

EtOrbi::EoTime.new(0, "UTC") < Object.new raises NoMethodError before, ArgumentError after.

The focused check covers <, <=, >, >= and <=>. Valid numeric and Time comparisons remain unchanged.

Verification

• Ruby 4.0.6 via rbenv; existing Probatio suite, no test files added or modified.
• Reviewed master baseline and this individual patch each run 270 tests / 412 assertions with exactly the same three pre-existing DST/rday failures from rday / rweek calculation is odd in time zones with DST #51. Failure identities were compared, not just counts.
• A release-based 1.4.1 branch containing the five separately proposed fixes passes 263 existing tests / 405 assertions with TZInfo 2.0.6 in UTC, Asia/Tokyo, America/Chicago, Europe/Istanbul and the detected local zone.
• Temporary focused before/after reproductions pass with TZInfo 2.0.6 and 1.2.11. The combined release branch also passes the existing TZInfo 1.2.11 suite at seed 36231. Seed 99751 has the same pre-existing Zulu test-order failure on both unmodified release and patched release: a test mutates the cached TZInfo object's comparison method.
• Ruby syntax and gem packaging checks pass. Targeted Lint passes on the combined branch with the existing, unrelated AssignmentInCondition warning excluded; no lint configuration was changed.

The current master's unreleased day-delta change was not brought into the consumer branch. No live scheduler or production operations were used. Linux/Windows and other Ruby runtimes were not run locally.

Breaking changes and limitations

Intentional exception-class correction: unsupported operands now raise ArgumentError rather than the accidental NoMethodError. No accepted operand types or comparison arithmetic changed. No overlapping current fix was found.