Prop 66: Activate the M013 Burn Pool (Phase 1): stream 15.0% of community-pool revenue to burn

Bootstrap the Economic Reboot's M013 Burn Pool with NO chain upgrade, effective the moment it passes. This is a standard x/protocolpool action: (1) enable uregen distribution, then (2) create a continuous fund routing 15.0% of community-pool revenue (validator block rewards = inflation + fees) to the null burn address (removed from circulation, on-chain). It turns real network revenue into standing deflationary pressure on REGEN — the market-side complement to the mint-params fix (prop #64). Honest scope: Regen Ledger has no supply-burn module yet, so this REMOVES REGEN from circulation (permanently unspendable); a true total-supply burn arrives with the full M013 x/feerouter + x/supply upgrade (Phase 2). The burn share is a governance dial (15.0% here, per the WG's current M013 figure) and can be adjusted or cancelled anytime (MsgCancelContinuousFund). Continues the contributor work behind the Economic Reboot framework.