feat: add rehearsal task for governance upgrade

[0xniha]

Description

This PR adds Rehearsal 4: Governor Upgrade, enabling the Security Council to practice upgrading the Optimism Governor contract through an L1 deposit.

Task Implementation

• Task: Complete rehearsal task using the L1PortalExecuteL2Call template.
• Implements governor upgrade execution via L1 deposit transaction.

Documentation

• Security Council Workflow: Step-by-step guide for Security Council members to execute the rehearsal.
• L2 Simulation Guide: Detailed walkthrough for manually simulating the L2 upgrade execution in Tenderly.

  State Override Required: The simulation requires setting OptimismGovernorProxy admin to L2ProxyAdmin via state override, because assumes this ownership to perform the upgrade.

Additional Changes

• Fixed incorrect file paths in documentation references in README.md.

[graphite-app]

When reviewing Superchain Ops tasks and templates, look for places that the tasks/templates can be made more robust, safer, etc. The documentation link src/tasks/<network>/rehearsals/<rehearsal-task-name>/README.md uses placeholder text instead of an actual file path with proper extension. This makes the documentation less robust as users cannot follow the link to see an actual example. To make this more robust, either provide a real example link or clarify that this is a template path that should be replaced with actual values.

Suggested change

	For posterity, you should make a `README.md` file in the tasks directory that contains a link to the executed transaction e.g. see [here](src/tasks/<network>/rehearsals/<rehearsal-task-name>/README.md).
	For posterity, you should make a `README.md` file in the tasks directory that contains a link to the executed transaction e.g. see [here](https://github.com/ethereum-optimism/superchain-ops/blob/main/src/tasks/op-mainnet/rehearsals/2023-10-25-ecotone-upgrade/README.md).

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[graphite-app]

When reviewing Superchain Ops tasks and templates, look for places that the tasks/templates can be made more robust, safer, etc. The configuration file is missing a newline at the end of the file (indicated by the '' character). This can cause issues with some tools and version control systems. To make this more robust, ensure the file ends with a proper newline character.

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[graphite-app]

The directory path in the simulation guide contains a typo. The path should be 2025-11-07-R4-governance-upgrade (matching the actual directory name created in the PR) instead of 2025-11-07-R4-governor-upgrade. This inconsistency would cause the command to fail when users attempt to follow the simulation instructions.

Suggested change

	cd src/tasks/eth/rehearsals/2025-11-07-R4-governor-upgrade
	cd src/tasks/eth/rehearsals/2025-11-07-R4-governance-upgrade

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[graphite-app]

The directory name rehearsal-4-noop-upgrade doesn't match the title in the README which describes this as a "Governor Upgrade" rehearsal. For consistency, consider renaming the directory to rehearsal-4-governor-upgrade to accurately reflect the purpose of this rehearsal task.

Suggested change

	4. [rehearsal-4-noop-upgrade](./rehearsal-4-noop-upgrade/README.md)
	4. [rehearsal-4-governor-upgrade](./rehearsal-4-governor-upgrade/README.md)

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