add conditional check for the lottie expressions support

[hermet]

No description provided.

[Copilot]

🟡 Changes recommended

Example.h now unconditionally includes the Lottie header, which can break non-Lottie builds even when the build system skips compiling Lottie examples.

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Pull request overview

This PR updates the ThorVG example set to better handle builds where Lottie expressions are unavailable, primarily by adding runtime guards in the expressions-dependent examples and refactoring header includes.

Changes:

• Add runtime tvg::LottieAnimation::expressions() checks to skip running expressions-dependent Lottie examples when unsupported.
• Refactor Lottie header inclusion by moving thorvg_lottie.h into the shared Example.h.
• Adjust PictureTransform example behavior (scaling line commented out) and update its tvgexam::main(...) invocation parameters.

File summaries

File	Description
src/PictureTransform.cpp	Updates example runtime behavior and tvgexam::main(...) arguments.
src/LottieTweening.cpp	Removes direct Lottie header include (now relies on Example.h).
src/LottieSlot.cpp	Adds expressions support guard before running the example; removes direct Lottie header include.
src/LottieInteraction.cpp	Adds expressions support guard before running the example; removes direct Lottie and math header includes.
src/LottieExpressions.cpp	Adds expressions support guard before running the example.
src/Example.h	Adds shared inclusion of thorvg_lottie.h for examples.

Review details

• Files reviewed: 6/6 changed files
• Comments generated: 2
• Review effort level: Lite

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[Copilot]

🔵 Needs a closer look

Example.h now unconditionally includes the Lottie header, which can break compilation of non-Lottie examples when Lottie headers are not installed.

Review details

• Files reviewed: 3/3 changed files
• Comments generated: 0 new
• Review effort level: Lite

[Copilot]

🟢 Approval recommended

The change is low-risk and behaviorally scoped to example startup, with only a minor best-practice improvement suggested regarding explicit <cmath> inclusion.

Review details

• Files reviewed: 3/3 changed files
• Comments generated: 1
• Review effort level: Lite