feat: architecture refactor — validators, positions, menuUtils, ESLint, tests, CI

Major improvements across the codebase:

- Extract validationUtils.js (548→217 lines) into strategy pattern validators
- Extract menuUtils.js (543→35 lines) into 6 focused menu modules
- Adopt POSITIONS constants across 23 files (183 replacements)
- Eliminate all 71 ESLint warnings (0 errors, 0 warnings)
- Add 158 unit tests for ConfigManager, MeasurementContainer, ValidationUtils
- Add architecture documentation with Mermaid diagrams
- Add CI pipeline (Docker, ESLint, Jest, Makefile)
- Add E2E infrastructure (docker-compose.e2e.yml)

Test results: 377 total (230 Jest + 23 node:test + 124 legacy), all passing
Lint: 0 errors, 0 warnings

Closes #2, #3, #9, #13, #14, #18

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

jest.config.js

@@ -0,0 +1,12 @@
+module.exports = {
+  testEnvironment: 'node',
+  verbose: true,
+  testMatch: [
+    '<rootDir>/nodes/generalFunctions/src/coolprop-node/test/**/*.test.js',
+    '<rootDir>/nodes/generalFunctions/test/**/*.test.js',
+  ],
+  testPathIgnorePatterns: [
+    '/node_modules/',
+  ],
+  testTimeout: 15000,
+};