fix(ci): allow Composer validation warnings (#4)

[MiddleSokilAI]

Problem

Composer validation stops CI before dependency installation because the existing wildcard constraints for seiger/sapi and seiger/stask generate warnings under --strict.

Fixes #4.

Change

This branch removes --strict from the validation step in .github/workflows/ci.yml and the validate:composer script in composer.json. Validation still rejects invalid configuration; dependency warnings remain visible without failing the build. Dependency constraints are unchanged. Public MCP contract impact: none.

Verification

• Reproduced the original strict-validation failure with exit code 1.
• composer validate — passed, exit code 0, with the expected wildcard warnings.
• composer run validate:composer — passed, exit code 0.
• php tests/Phase6/CiWorkflowCoverageTest.php — passed.
• git diff --check — passed.

Remaining checks

Full dependency installation and runtime integration tests were not run locally. Remote CI results remain pending.