Add event action to week and day calendar views

[keilogic]

Fixes #1108

Summary

• adds an Add event icon button to the calendar toolbar in week and day views
• keeps month view unchanged, where each visible day already has its own add button
• keeps mwlView synchronized whenever setView() runs, even when the selected view already matches the stored preference

Tests

• npx ng test --include src/app/calendar-app/calendar-app.component.spec.ts --watch=false --browsers=FirefoxHeadless
• npx tsc -p src/tsconfig.app.json --noEmit
• npx tsc -p src/tsconfig.spec.json --noEmit
• npm run lint -- --quiet
• npm run policy
• SKIP_CHANGELOG=1 node src/build/pre-build.js && npx ng build runbox7 --configuration production --base-href=/app/ && node src/build/post-build.js

AI disclosure

AI assistance used: OpenAI Codex in the local development workspace. The agent was used for code edits, tests, validation commands, and PR text preparation.