ci(ci): remove legacy Basic Memory workflow

[phernandez]

Summary

• Removes the legacy GitHub Actions Basic Memory Project Updates workflow.
• The old workflow used openai/codex-action and consumed OpenAI API credits.
• Project-update notes are now handled by the Hermes Auto BM GitHub webhook instead.

Test Plan

• Verified the only staged change is deletion of .github/workflows/basic-memory.yml.
• Verified .github/basic-memory/ config, prompt, and SOUL files remain in place for the webhook runner.
• Verified no remaining workflow references to openai/codex-action, OPENAI_API_KEY, or Basic Memory Project Updates under .github/workflows.

[CLAassistant]

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