PHP SDK: add examples and examples-php component

[countradooku]

Follow-up from the experimental PHP SDK review.

Every other SDK has examples wired through repository component detection, but the PHP SDK does not yet have examples/php/ examples or an examples-php component entry. This is fine as a follow-up and not a merge blocker, but should be tracked so it does not get lost.

Scope

• Add examples/php/ examples following the shape and coverage expectations of the other SDK example directories.
• Add an examples-php component entry in .github/config/components.yml.
• Wire the component paths so PHP example changes trigger the expected CI tasks.
• Ensure the examples component depends on the PHP SDK and any required Rust server / CI infrastructure components.

References

• examples/python/, examples/node/, examples/go/, examples/java/, examples/csharp/, examples/rust/
• .github/config/components.yml

Related: #3302
Initial PHP SDK work: #3235