Burn Root Prop

[JohnReedV]

Description

This PR adds a root-only admin-utils call to burn root prop proceeds instead of paying root yield.

• Adds a BurnRootProp toggle
• Adds a root-only sudo_set_burn_root_prop dispatch
• Sets reported root yield/proportion to zero across subnets while enabled
• Preserves root prop sell pressure by still routing root yield through the subnet pool
• Burns the resulting TAO after the root yield sells through the pool
• Forces root claims through the sell path while enabled, even when the claim type is Keep
• Prevents root stakers from receiving root yield while enabled
• Preserves normal non-root subnet validator/server emission behavior
• Adds a unit test covering root-only access, zeroed root prop, sell-through-pool behavior, TAO burn, and blocked root-staker payout