[robertleifke]

Records the box changes of 2026-10-28 for MarginEngine v2's enable (#258), and brings the templates in line with what is installed. v2 is still closed.

• OPS_BOX_CHANGES.md: new entry.
  • The exchange-future-v2 checkout at 840526a.
  • The v2 relayer 0x3ACe…763f, funded with 0.003 ETH from v1's forward relayer.
  • numo-future-feeds-v2@cngn-30nov26 live. First mark: 0x9fbc6cbb…03bf.
  • The engine keeper moved from v1 to v2, and the pager moved to 840526a with ENGINE_V2_KEEPER_HEALTH_URL.
  • Also corrects the 2026-10-27 entry: /root/box-16.sh was removed (SSM 7f0db571).
• The keeper move. It's the same EOA 0x753f…f83b and key /numo/keeper/engine_keeper_key. Canary: check collateral backing, not just whether pricing works #33's 5,000 USDC moved to v2 account Wrapped-USDC quote leg: make the USDC side structurally 1:1 #38, and numo-engine-keeper (v1) is disabled. v1's USDC-cNGN-30NOV26 (22.696 contracts) has no liquidator until it settles on 30 Nov.
  • numo-engine-keeper-v2.service now names that key, so the box's drop-in can be removed when the unit is next copied.
  • engine-keeper-v2.env is updated to KEEPER_ACCOUNT=38 and DRY_RUN=false.
• Other templates: perp-pager.env now sets ENGINE_V2_KEEPER_HEALTH_URL, and the two v2 units and numo-engine-keeper.service describe what is installed.
• docs/margin-engine-v2.md: the step-3 note about FutureSymbol collisions is out of date since feat(markets): one reader per futures series; list MarginEngine v2's <BASE>-<expiry> beside v1 #280, so it is replaced.

Not in this PR:

• The pager's --self-test at 840526a needs forge out/, so it has to run on a laptop.
• check_signer_balance.py watches neither forward relayer, and it runs from the pinned /home/ec2-user/exchange.
• SSM /numo/keeper/engine_v2_keeper_key (0x2d9C…) is unused and is to be deleted.