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>

.gitea/workflows/ci.yml

@@ -0,0 +1,41 @@
+name: CI
+
+on:
+  push:
+    branches: [main, develop, dev-Rene]
+  pull_request:
+    branches: [main]
+
+jobs:
+  lint-and-test:
+    runs-on: ubuntu-latest
+    container:
+      image: node:20-slim
+
+    steps:
+      - name: Install git
+        run: apt-get update -qq && apt-get install -y -qq git
+
+      - name: Checkout with submodules
+        uses: actions/checkout@v4
+        with:
+          submodules: recursive
+
+      - name: Rewrite generalFunctions to local path
+        run: |
+          sed -i 's|"generalFunctions": "git+https://[^"]*"|"generalFunctions": "file:./nodes/generalFunctions"|' package.json
+
+      - name: Install dependencies
+        run: npm install --ignore-scripts
+
+      - name: Lint
+        run: npm run lint
+
+      - name: Test (Jest)
+        run: npm test
+
+      - name: Test (node:test)
+        run: npm run test:node
+
+      - name: Test (legacy)
+        run: npm run test:legacy