feat: birthday tracking, dashboard KPIs, and app name customization (#88)

- Add Birthdays module: CRUD with calendar/reminder auto-sync, photo upload, age notes
- Add DB migration 18 (birthdays table with calendar_event_id, trigger, indexes)
- Add dashboard widgets: birthdays, family participants, budget overview
- Add Settings > General: admins can set a custom app name (reflected in title/sidebar/login)
- Improve service worker: network-first caching for mutable JS/CSS assets
- Add translations for 16 locales (birthday keys)

Fixes applied during integration:
- innerHTML replaced with insertAdjacentHTML/replaceChildren throughout birthdays.js and dashboard.js
- docker-compose.yml personal dev changes reverted

Co-authored-by: Rafael Foster <rafaelgfoster@gmail.com>
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/locales/en.json

@@ -38,6 +38,7 @@
     "shopping": "Shopping",
     "notes": "Board",
     "contacts": "Contacts",
+    "birthdays": "Birthdays",
     "budget": "Budget",
     "settings": "Settings",
     "main": "Main navigation",
@@ -82,6 +83,19 @@
     "allDay": "All day",
     "shoppingMore": "+{{count}} more",
     "weather": "Weather",
+    "familyMembers": "Family members",
+    "participantsAdded": "participants added",
+    "upcomingBirthdays": "Upcoming birthdays",
+    "noBirthdays": "No birthdays yet",
+    "daysLeft": "{{count}} days",
+    "budgetOverview": "Budget overview",
+    "monthlyIncome": "Income",
+    "monthlyExpenses": "Expenses",
+    "monthlyBalance": "Balance",
+    "savingsRate": "Savings rate",
+    "topExpense": "Top expense",
+    "budgetEntries": "Entries",
+    "noBudgetData": "No budget data this month.",
     "customize": "Customize",
     "customizeTitle": "Customize widgets",
     "customizeReset": "Reset",
@@ -537,6 +551,7 @@
     "tabAccount": "Account",
     "tabsAriaLabel": "Settings sections",
     "sectionDesign": "Appearance",
+    "sectionAppName": "Application name",
     "sectionShopping": "Shopping",
     "shoppingCategoriesLabel": "Shopping Categories",
     "shoppingCategoriesHint": "Add, rename, delete or reorder categories.",
@@ -554,6 +569,16 @@
     "sectionCalendarSync": "Calendar Sync",
     "sectionFamily": "Family Members",
     "cardAppearance": "Display",
+    "appNameTitle": "App name",
+    "appNameLabel": "Application name",
+    "appNameHint": "This name appears in the sidebar, browser title and login screen.",
+    "appNamePlaceholder": "Oikos",
+    "appNameSavedToast": "Application name saved.",
+    "sectionDate": "Date",
+    "dateFormatTitle": "Date format",
+    "dateFormatLabel": "Preferred date format",
+    "dateFormatHint": "Choose how dates are displayed throughout the app.",
+    "dateFormatSavedToast": "Date format saved.",
     "themeSystem": "System",
     "themeSysLabel": "Use system setting",
     "themeLight": "Light",
@@ -751,6 +776,35 @@
     "pendingBadgeTitle": "{{count}} reminder due",
     "pendingBadgeTitlePlural": "{{count}} reminders due"
   },
+  "birthdays": {
+    "title": "Birthdays",
+    "addButton": "Add birthday",
+    "searchPlaceholder": "Search birthdays…",
+    "upcomingTitle": "Next birthdays",
+    "upcomingHint": "The next people to celebrate, already synced to the calendar.",
+    "peopleTitle": "People",
+    "peopleHint": "Search, review and edit every saved birthday.",
+    "emptyTitle": "No birthdays yet",
+    "emptyDescription": "Add a birthday to keep it visible in the calendar and reminders.",
+    "newTitle": "New birthday",
+    "editTitle": "Edit birthday",
+    "nameLabel": "Name",
+    "birthDateLabel": "Birth date",
+    "photoLabel": "Profile picture",
+    "photoOptional": "Optional: you can save without a profile picture.",
+    "removePhoto": "Remove picture",
+    "notesLabel": "Notes",
+    "notesPlaceholder": "Gift ideas, favorite cake, family notes…",
+    "calendarHint": "Each birthday is automatically added to the calendar and reminder system.",
+    "requiredFields": "Name and birth date are required.",
+    "createdToast": "Birthday saved.",
+    "updatedToast": "Birthday updated.",
+    "deletedToast": "Birthday deleted.",
+    "deleteConfirm": "Delete birthday for \"{{name}}\"?",
+    "ageNoteToday": "Turns {{age}} today.",
+    "ageNoteTomorrow": "Turns {{age}} tomorrow.",
+    "ageNoteDays": "Turns {{age}} in {{days}} days."
+  },
   "recipes": {
     "title": "Recipes",
     "addRecipe": "Add recipe",