perf: fix stale auto-save bug + extract SettingsSidebar to lazy chunk

- saveSetting: add setProfile(p => ({...p, [key]: value})) so profile
  stays in sync with individual setting changes — prevents auto-save
  from overwriting fresh settings with stale profile object values
- Extract SettingsSidebar (4725 lines) from WeeklyView.tsx into its own
  file; lazy-load with next/dynamic so the ~4500-line settings panel
  is deferred until the user opens settings
- Extract shared constants/helpers to src/lib/:
  fontConstants.ts (AVAILABLE_FONTS, FONT_WEIGHTS, isCustomFont)
  weeklyViewTranslations.ts (translations object, ~1100 lines)
  weeklyViewConstants.ts (WeatherDisplayKey, WEATHER_DISPLAY_DEFAULTS)
- WeeklyView.tsx: 16,209 → 10,364 lines (-36%)

v1.80.0

package.json

@@ -1,6 +1,6 @@
 {
   "name": "my-weekly-todo-list",
-  "version": "1.79.0",
+  "version": "1.80.0",
   "description": "A web-based weekly task management application that organizes to-dos and calendar events in a single, intuitive weekly view",
   "main": "index.js",
   "scripts": {

src/lib/fontConstants.ts

@@ -0,0 +1,28 @@
+// Font options shared between WeeklyView and SettingsSidebar
+
+export const AVAILABLE_FONTS = [
+    { name: "Default (Inter)", value: "Inter" },
+    { name: "Roboto", value: "Roboto" },
+    { name: "Open Sans", value: "Open Sans" },
+    { name: "Lato", value: "Lato" },
+    { name: "Montserrat", value: "Montserrat" },
+    { name: "Oswald", value: "Oswald" },
+    { name: "Raleway", value: "Raleway" },
+    { name: "Playfair Display", value: "Playfair Display" },
+    { name: "Merriweather", value: "Merriweather" },
+    { name: "Nunito", value: "Nunito" },
+    { name: "Dancing Script", value: "Dancing Script" },
+    { name: "Pacifico", value: "Pacifico" },
+    { name: "Custom Google Font...", value: "__custom__" },
+];
+
+// Check if a font value is a custom (non-preset) font
+export const isCustomFont = (value: string): boolean =>
+    !!value && value !== "__custom__" && !AVAILABLE_FONTS.slice(0, -1).some((f) => f.value === value);
+
+export const FONT_WEIGHTS = [
+    { name: "Light", value: "300" },
+    { name: "Normal", value: "400" },
+    { name: "Medium", value: "500" },
+    { name: "Bold", value: "700" },
+];

src/lib/weeklyViewConstants.ts

@@ -0,0 +1,4 @@
+// Shared constants for WeeklyView and SettingsSidebar
+
+export type WeatherDisplayKey = "icon" | "temp" | "feelsLike" | "wind" | "gusts" | "precipProb" | "precip" | "humidity" | "uv";
+export const WEATHER_DISPLAY_DEFAULTS: WeatherDisplayKey[] = ["icon", "temp"];