Increase ARM-stETH Ark allocation cap (SIP2.21)

Hey @pete thanks for putting this together!

Just noting for context: this proposal has been recategorized from a SIP to a “Risk” topic, since **adjusting allocation caps is handled operationally by @BlockAnalitica rather than through onchain governance. Governance already approved the strategy onboarding in SIP2.21, so any future cap adjustments fall under the risk management and parameter tuning process.

That said, great to see this data and performance breakdown, as it provides strong signal for why a cap increase could make sense from a yield optimization perspective. Curious to hear from @BlockAnalitica on this matter!