feat(commands): unit shorthand + declare units on physical setters; wiki sync

- data.flow: units:{measure,default} -> unit:'m3/h'.
- set.water-height -> unit:'m'; set.header-pressure -> unit:'mbar' (matches the
  domain setters' expected units; no-unit input passes through unchanged).
- Regenerate wiki topic-contract (Unit column).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

wiki/Reference-Contracts.md

@@ -19,8 +19,8 @@ The registry lives in `src/commands/index.js`. Each descriptor maps a canonical
 |---|---|---|---|---|
 | `data.flow` | `air_flow` | `number` | `volumeFlowRate` (default `m3/h`) | Push the measured air flow into the diffuser model. |
 | `set.density` | `density` | `number` | — | Update the air density used in OTR / SOTR calculations. |
-| `set.water-height` | `height_water` | `number` | — | Update the water column height above the diffusers (m). |
-| `set.header-pressure` | `header_pressure` | `number` | — | Update the header (supply) pressure feeding the diffusers (mbar). |
+| `set.water-height` | `height_water` | `number` | `length` (default `m`) | Update the water column height above the diffusers (m). |
+| `set.header-pressure` | `header_pressure` | `number` | `pressure` (default `mbar`) | Update the header (supply) pressure feeding the diffusers (mbar). |
 | `set.elements` | `elements` | `number` | — | Update the count of active diffuser elements. |
 | `set.alfa-factor` | `alfaFactor` | `number` | — | Update the alfa factor used in oxygen-transfer correction. |