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>

docker-compose.yml

@@ -0,0 +1,39 @@
+services:
+  ci:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    command: npm run ci
+    environment:
+      - NODE_ENV=test
+      - CI=true
+
+  lint:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    command: npm run lint
+
+  test:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    command: npm run test:all
+
+  test-jest:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    command: npm test
+
+  test-node:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    command: npm run test:node
+
+  test-legacy:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    command: npm run test:legacy