minor fixes

[mercury233]

No description provided.

[Copilot]

Pull request overview

Minor cleanups across three files: refactoring extension checks to use the existing IsExtension helper, replacing a magic number with a named constant, reusing already-declared loop-scope variables, and returning a more meaningful exit code on initialization failure.

Changes:

• gframe.cpp: Replace inline extension-suffix comparisons with ygo::IsExtension, and return EXIT_FAILURE instead of 0 when initialization fails.
• single_mode.cpp: Reuse the function-scoped player / count variables in the MSG_HINT and MSG_SHUFFLE_HAND cases instead of redeclaring locals.
• data_manager.cpp: Use SIZE_SETCODE constant instead of literal 10 in the setcode loop.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
gframe/gframe.cpp	Use IsExtension helper for .ydk/.yrp checks; return EXIT_FAILURE on init failure.
gframe/single_mode.cpp	Reuse outer-scope player/count variables in MSG_HINT and MSG_SHUFFLE_HAND.
gframe/data_manager.cpp	Replace magic number 10 with SIZE_SETCODE in FormatSetName.

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