feat: add transitions and micro-interactions across all views

- Page transitions with slide-up/fade on route changes (App.vue)
- NavRail sliding active indicator with spring-like easing
- List enter/leave/move animations on Entries, Projects, Clients, Timer
- Modal enter/leave transitions with scale+fade on all dialogs
- Dropdown transitions with overshoot on all select/picker components
- Button feedback (scale on hover/active), card hover lift effects
- Timer pulse on start, glow on stop, floating empty state icons
- Content fade-in on Dashboard, Reports, Calendar, Timesheet
- Tag chip enter/leave animations in AppTagInput
- Progress bar smooth width transitions
- Implementation plan document

src/App.vue

@@ -79,7 +79,11 @@ watch(() => [settingsStore.settings.shortcut_toggle_timer, settingsStore.setting
     <div class="flex-1 flex overflow-hidden">
       <NavRail />
       <main class="flex-1 overflow-auto">
-        <router-view />
+        <router-view v-slot="{ Component }">
+          <Transition name="page" mode="out-in">
+            <component :is="Component" :key="$route.path" />
+          </Transition>
+        </router-view>
       </main>
     </div>
   </div>