tools: add contract-verify and flow-lint (JS native, repo-rule-aware)

- tools/contract-verify/ — diffs CONTRACT.md ## Inputs table vs
  src/commands/index.js registry. First run found 3 real drifts:
  MGC has `set.scaling` in CONTRACT (not in registry); monster + settler
  registry has `child.register` (not in CONTRACT); pumpingStation registry
  has `set.outflow` (not in CONTRACT).
- tools/flow-lint/ — lints examples/*.flow.json against the rules in
  .claude/rules/node-red-flow-layout.md. First run flagged the
  monster/basic flow (4 ui-* at 0,0 + ui-chart missing interpolation
  property) and rotatingMachine/edge.flow.json (6 ui-* at 0,0).
- Both tools are read-only, single-binary npm packages with a `--json`
  output mode for CI, exit code 1 on drift. Encode the rules so we
  don't have to re-discover the bugs that motivated them.

Per CLAUDE.md tooling doctrine: prefer these over ad-hoc grep/jq.

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

tools/flow-lint/package.json

@@ -0,0 +1,13 @@
+{
+  "name": "@evolv/flow-lint",
+  "version": "0.1.0",
+  "private": true,
+  "description": "Lint Node-RED flows (examples/*.flow.json) against EVOLV flow-layout rules",
+  "bin": {
+    "evolv-flow-lint": "bin/flow-lint.js"
+  },
+  "scripts": {
+    "test": "node --test test/*.test.js"
+  },
+  "license": "UNLICENSED"
+}