docs + submodules: final backlog clearance — valve/reactor/dashboardAPI

Superproject:
- CLAUDE.md: legacy-drift table loses the dashboardAPI row (migrated);
  drift section notes the type-id-preservation strategy for the
  remaining mgc / vgc renames.
- CONTRACTS.md: canonical-unit rule explicitly carves out reactor as
  an approved ASM-textbook exception with the conversion boundary.

Submodules:
- nodes/valve @ 167b102: CONTRACT documents valve's lack of an FSM
  maintenance state (schema mode enum accepts `maintenance` but no
  enter/exit sequences exist). Limits made explicit instead of being
  hidden as a wiki TODO.
- nodes/reactor @ 75d0413: CONTRACT now declares the approved ASM-unit
  divergence (mg/L, m³/d, °C, 1/h) with the conversion boundary spelled
  out. Closes the canonical-unit drift surfaced by the wiki audit.
- nodes/dashboardAPI @ ......: file rename (preserves type id).

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

CONTRACTS.md

@@ -126,6 +126,11 @@ idempotent setters, `cmd.<verb>` for triggers, `evt.<noun>` for events.
 Tests live in `test/{basic,integration,edge}/`. Submodule commits go in the
 submodule first, then the superproject bumps the pin.
 
+**Canonical units** (Pa / m³/s / W / K) apply to every node **except
+`reactor`**, which deliberately uses ASM-kinetics literature units
+(mg/L, m³/d, °C, 1/h) — documented in `nodes/reactor/CONTRACT.md`.
+Conversions happen at the parent/child boundary via `UnitPolicy`.
+
 ---
 
 ## 7. Verification checklist before merge