[codex] PR_26175_ALFA_006 game hub create project validation

[ToolboxAid]

Summary

• Replaced the active BUILD_PR.md with PR_26175_ALFA_006 as the source of truth.
• Added Game Hub page-level validation for the add-game row so signed-in creators cannot silently create fallback Untitled Game projects from blank or whitespace-only names.
• Marks the create-row game name input as required/invalid and reports Enter a game name before saving. through the existing Game Hub status log.
• Added targeted Playwright coverage plus ALFA_006 reports, changed-files report, review diff, and repo-structured delta ZIP metadata.

Validation

• PASS: npx playwright test tests/playwright/tools/GameHubMockRepository.spec.mjs --workers=1 --grep "Game Hub creates, opens, and deletes mock games" ran 1 test: 1 passed, 0 failed.
• PASS: changed-source style scan found no inline style or style-block matches.
• PASS: git diff --cached --check before commit.

Notes

• No API/service/repository contract changes.
• Guest save redirect behavior is preserved because auth gating still runs before create-row validation.
• Delta ZIP: tmp/PR_26175_ALFA_006-game-hub-create-project-validation_delta.zip.
• Commit: e5d71a88c62f645ba67c38db879b16daa0927d46.