[codex] Remove personal branding from public pages

[GalaxyRuler]

Summary

• Replace public page header marks with the supplied no-name logo asset.
• Keep visible public branding on project wording only.
• Refresh the dark README/banner branding and tests so the old inline mark does not return.

Validation

• python -m black --check tests\test_playground_examples.py
• python -m ruff check tests\test_playground_examples.py
• git diff --check
• python -m pytest tests\test_playground_examples.py tests\aliases\test_pygame.py
• Browser smoke test: no old inline logo, no personal-branding text hit, no page error beyond the existing browser audio deprecation warning.