feat(notes): wire app with floating add button

src/App.tsx

@@ -1,5 +1,68 @@
+import { useState } from 'react'
+import { useNotes } from './hooks/useNotes'
+import NoteList from './components/NoteList'
+import NoteEditor from './components/NoteEditor'
+import FloatingButton from './components/FloatingButton'
+
 function App() {
-  return <main></main>
+  const { notes, addNote, updateNote, deleteNote } = useNotes()
+  const [selectedId, setSelectedId] = useState<number | null>(null)
+  const [createdId, setCreatedId] = useState<number | null>(null)
+
+  const selectedNote = notes.find((note) => note.id === selectedId) ?? null
+
+  const createNote = () => {
+    const note = addNote()
+    setSelectedId(note.id)
+    setCreatedId(note.id)
+  }
+
+  const handleUpdate = (id: number, patch: Parameters<typeof updateNote>[1]) => {
+    updateNote(id, patch)
+    if (id === createdId) setCreatedId(null)
+  }
+
+  const handleDelete = (id: number) => {
+    deleteNote(id)
+    setSelectedId(null)
+  }
+
+  return (
+    <main className="mx-auto w-full max-w-2xl flex flex-col min-h-screen">
+      <header className="sticky top-0 bg-white border-b border-gray-200 px-4 py-3">
+        {selectedNote ? (
+          <div className="flex items-center gap-2">
+            <button
+              type="button"
+              onClick={() => setSelectedId(null)}
+              aria-label="Retour"
+              className="w-10 h-10 rounded-full text-xl hover:bg-gray-100"
+            >
+              ←
+            </button>
+            <h1 className="text-lg font-semibold">Notes</h1>
+          </div>
+        ) : (
+          <h1 className="text-lg font-semibold">Notes</h1>
+        )}
+      </header>
+
+      <section className="flex-1 px-4 py-4">
+        {selectedNote ? (
+          <NoteEditor
+            note={selectedNote}
+            onUpdate={handleUpdate}
+            onDelete={handleDelete}
+            autoEdit={selectedId === createdId}
+          />
+        ) : (
+          <NoteList notes={notes} onSelect={setSelectedId} />
+        )}
+      </section>
+
+      <FloatingButton onClick={createNote} />
+    </main>
+  )
 }
 
 export default App