[Refactor] Improve fork from old block.

[clement-ux]

Summary

Replaces the manual proposalExecuted boolean and maxDeploymentFiles sliding window with automatic, timestamp-based governance tracking in the deployment framework.

• Split timestamp into timestampDep / timestampGov in the Execution struct and deployment JSON files. timestampGov == 0 means governance is still pending; once confirmed on-chain the timestamp is recorded automatically.
• Remove proposalExecuted from all deployment scripts (~20 files). Governance completion is now derived from timestampGov instead of requiring a manual boolean flip per script.
• Remove maxDeploymentFiles sliding window in DeployManager. Instead of only processing the last N scripts, all scripts are iterated and those fully executed (both timestamps set and <= block.timestamp) are skipped via a fast-path check on the filename.
• Add UpdateGovernance.s.sol (make update-governance), a new CLI tool that forks mainnet, iterates executions with timestampGov == 0, rebuilds their governance proposals, computes proposal IDs, checks on-chain state via IGovernance.state(), and writes updated timestamps back to the deployment JSON.
• Refactor Resolver: replace executionExists mapping with depTimestamp, govTimestamp, and executionIndex mappings. Add addGovernanceTimestamp() for updating governance state after the fact.
• Normalize contract names to match filenames (e.g. $003_UpgradeLidoARMMainnetScript -> $003_UpgradeLidoARMScript), enabling the filename-based fast-path skip in DeployManager.
• Add restoreBlockAndTimestamp modifier on GovHelper.simulate() so governance simulation doesn't permanently alter block.number / block.timestamp.
• Extract _extractScriptName helper in Base.s.sol (shared by DeployManager and UpdateGovernance).
• Update deployment JSONs: migrate all executions to the new timestampDep/timestampGov format, add missing contracts (MORPHO_MARKET_ORIGIN, MORPHO_MARKET_ORIGIN_IMPL), update OETH_ARM_IMPL address, delete stale deployments-17000.json (Holesky).

[clement-ux]

I'll try something better.