fix(CONTRACT): remove stale set.scaling row — topic removed in refactor

groupcontrol.test.js comment confirms `setScaling is gone — handleInput
now takes canonical m³/s directly` since the refactor. CONTRACT.md
still listed it; contract-verify now agrees with the registry.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CONTRACT.md

@@ -8,7 +8,6 @@ Hand-maintained for Phase 4; the `## Inputs` table is generated from
 | Canonical | Aliases (deprecated) | Payload | Effect |
 |---|---|---|---|
 | `set.mode` | `setMode` | `string` — one of `prioritycontrol`, `optimalcontrol`, `dynamiccontrol`, … | Switches the control strategy via `source.setMode(payload)`. |
-| `set.scaling` | `setScaling` | `string` — one of `absolute`, `normalized` | Sets the demand-scaling convention via `source.setScaling(payload)`. |
 | `child.register` | `registerChild` | `string` — the child node's Node-RED id | Resolves the child via `RED.nodes.getNode` and registers it through `childRegistrationUtils.registerChild(childObj.source, msg.positionVsParent)`. |
 | `set.demand` | `Qd` | numeric (number or numeric string) | Calls `source.handleInput('parent', parseFloat(payload))`. On success, replies on Port 0 with `topic = source.config.general.name`, `payload = 'done'`. Non-numeric payloads log `error` and are skipped. |