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>

scripts/patch-deps.js

@@ -0,0 +1,20 @@
+/**
+ * Preinstall script: rewrites the generalFunctions dependency
+ * from git+https to a local file path when the submodule exists.
+ * This avoids needing Gitea credentials during npm install.
+ */
+const fs = require('fs');
+const path = require('path');
+
+const pkgPath = path.join(__dirname, '..', 'package.json');
+const localGF = path.join(__dirname, '..', 'nodes', 'generalFunctions');
+
+if (fs.existsSync(localGF) && fs.existsSync(path.join(localGF, 'index.js'))) {
+  const pkg = JSON.parse(fs.readFileSync(pkgPath, 'utf8'));
+  if (pkg.dependencies && pkg.dependencies.generalFunctions &&
+      pkg.dependencies.generalFunctions.startsWith('git+')) {
+    pkg.dependencies.generalFunctions = 'file:./nodes/generalFunctions';
+    fs.writeFileSync(pkgPath, JSON.stringify(pkg, null, 2) + '\n');
+    console.log('[patch-deps] Rewrote generalFunctions to local path');
+  }
+}