Add webapp subproject (Vite + TypeScript + Web Components)

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

webapp/src/components/days-page.ts

@@ -0,0 +1,30 @@
+import { api, DaySummary } from '../api'
+import { navigate } from '../router'
+
+export class DaysPage extends HTMLElement {
+  async connectedCallback(): Promise<void> {
+    this.innerHTML = '<p>Lade...</p>'
+    try {
+      const days = await api.getDays()
+      if (days.length === 0) {
+        this.innerHTML = '<p>Noch keine Einträge.</p>'
+        return
+      }
+      this.innerHTML = '<h1>Tage</h1><ul id="days-list"></ul>'
+      const list = this.querySelector('#days-list')!
+      for (const day of days) {
+        const li = document.createElement('li')
+        const a = document.createElement('a')
+        a.href = `/days/${day.date}`
+        a.textContent = `${day.date} (${day.count} Punkte)`
+        a.addEventListener('click', (e) => { e.preventDefault(); navigate(`/days/${day.date}`) })
+        li.appendChild(a)
+        list.appendChild(li)
+      }
+    } catch (err) {
+      this.innerHTML = `<p>Fehler: ${err}</p>`
+    }
+  }
+}
+
+customElements.define('days-page', DaysPage)