chore(sepolia): add incident multisig signer replacement task

[leopoldjoy]

Summary

• Add a Sepolia task to replace 0x72069542Ca378553A3D479c82Adc31f21CA6dE4a with 0x2c1475476B586d66a85bC65A5aB396BBbAa4f3aD.
• Apply the same owner diff to the Incident Multisig and mock Security Council Safe.
• Preserve each Safe threshold and owner count, with signer and facilitator documentation for both roles.
• Include generated validation files and successful execution artifacts for both Safes.

Validation

• make validate-config
• mise exec -- forge fmt --check
• mise exec -- forge build --force
• Full fork signing simulations for both Sepolia Safes, including prechecks and postchecks
• Both validation files pass the signer tool TaskConfigSchema
• Independent security-focused review with no findings
• Both transaction receipts have status 1 and emit the expected owner addition and removal events
• Post-execution RPC checks confirm 12 owners and unchanged thresholds of 3 and 1

Execution

• Incident Multisig: https://sepolia.etherscan.io/tx/0x67f0110015d7854276b90bb8e3915b44d6aba2022b06d1994454d101dc3dd6b3
• Mock Security Council Safe: https://sepolia.etherscan.io/tx/0x0e33d244f0c2ebf1c938eb67e746fc02a91652621ae48b32f41be95b721bd11c

Notes

• Task-origin validation is explicitly disabled for both Sepolia validation files, matching the prior task.

[cb-heimdall]

✅ Heimdall Review Status

Requirement	Status	More Info
Reviews	✅ 2/2	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 2 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 2 2 1 if commit is unverified 0 Sum 2

Approved review 4776476365 from roger-bai-coinbase is now dismissed due to new commit. Re-request for approval.