feat: L'Ami Fiduciaire V1.0.0 — full codebase with Story 0.1 complete

Initial commit of the L'Ami Fiduciaire SaaS platform built on Laravel 12,
Vue 3, Inertia.js 2, and Tailwind CSS 4.

Story 0.1 (rename folders to declarations in database) is implemented and
code-reviewed: migration, rollback, and 6 Pest tests all passing.

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

app/Http/Controllers/Client/ConfirmController.php

@@ -0,0 +1,57 @@
+<?php
+
+namespace App\Http\Controllers\Client;
+
+use App\Enums\ActorType;
+use App\Http\Controllers\Controller;
+use Illuminate\Http\RedirectResponse;
+use Illuminate\Http\Request;
+use Inertia\Inertia;
+use Inertia\Response;
+
+class ConfirmController extends Controller
+{
+    /**
+     * Show the confirmation page.
+     */
+    public function show(Request $request, string $token): Response
+    {
+        $invitation = $request->attributes->get('folder_invitation');
+        $folder = $invitation->folder;
+
+        $folder->load(['client']);
+
+        return Inertia::render('client/Confirm', [
+            'folder' => [
+                'id' => $folder->id,
+                'title' => $folder->title,
+                'client_name' => $folder->client->company_name,
+            ],
+            'token' => $token,
+            'submitUrl' => route('client.confirm.store', ['token' => $token]),
+        ]);
+    }
+
+    /**
+     * Store the confirmation (client confirms).
+     */
+    public function store(Request $request, string $token): RedirectResponse
+    {
+        $invitation = $request->attributes->get('folder_invitation');
+        $folder = $invitation->folder;
+
+        $request->validate([
+            'signature' => ['required', 'string', 'max:255'],
+        ]);
+
+        $folder->update([
+            'validated_at' => now(),
+            'confirmed_by_type' => ActorType::Client,
+            'confirmed_by_id' => $folder->client_id,
+            'confirmation_signature' => $request->input('signature'),
+            'status' => \App\Enums\FolderStatus::Validated,
+        ]);
+
+        return back()->with('flash', ['type' => 'success', 'message' => 'Validation enregistrée. Merci.']);
+    }
+}