feat(time-tracking) : add calendar page, timer sidebar, and all UI components

- SidebarTimer widget with play/stop button
- TimeEntryBlock with drag-to-move and resize
- TimeEntryDrawer for create/edit entries
- TimeEntryContextMenu for copy/paste/delete
- TimeTrackingCalendar grid with week/day view
- Time tracking page with filters and navigation
- Sidebar link and timer integration in layout
- TaskCard play button connected to timer store

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/nuxt.config.ts

@@ -17,10 +17,30 @@ export default defineNuxtConfig({
     ],
     runtimeConfig: {
         public: {
-            apiBase: process.env.NUXT_PUBLIC_API_BASE
+            apiBase: process.env.NUXT_PUBLIC_API_BASE || '/api'
         }
     },
-    devServer: {port: 3002},
+    devServer: {
+        port: 3002,
+    },
+    nitro: {
+        devProxy: {
+            '/api': {
+                target: 'http://nginx',
+                changeOrigin: true,
+            },
+        },
+    },
+    vite: {
+        server: {
+            proxy: {
+                '/api': {
+                    target: 'http://nginx',
+                    changeOrigin: true,
+                },
+            },
+        },
+    },
     toast: {
         settings: {
             timeout: 2000,