Documentation updates

[naddison36]

Summary

• Remove remaining OpenZeppelin Defender-specific configuration, signer handling, and test constants.
• Refresh repository documentation to reflect the current Foundry deployment framework, CI workflow, and supported networks.
• Update Talos documentation:
  • regenerate the action inventory from current action sources;
  • replace migration-focused action guidance with ongoing Talos action development and maintenance guidance;
  • remove obsolete Hardhat/Defender references.
• Remove stale historical records and unused Harvester documentation.