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/Middleware/EnsureUserHasWorkspace.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace App\Http\Middleware;
+
+use Closure;
+use Illuminate\Http\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+class EnsureUserHasWorkspace
+{
+    /**
+     * Handle an incoming request.
+     *
+     * @param  \Closure(\Illuminate\Http\Request): (\Symfony\Component\HttpFoundation\Response)  $next
+     */
+    public function handle(Request $request, Closure $next): Response
+    {
+        $workspaceId = $request->session()->get('current_workspace_id');
+
+        if (! $workspaceId) {
+            return redirect()->route('dashboard')
+                ->with('error', __('Please select a workspace first.'));
+        }
+
+        $user = $request->user();
+        $hasAccess = $user->workspaces()->where('workspaces.id', $workspaceId)->exists();
+
+        if (! $hasAccess) {
+            $request->session()->forget('current_workspace_id');
+
+            return redirect()->route('dashboard')
+                ->with('error', __('You do not have access to this workspace.'));
+        }
+
+        return $next($request);
+    }
+}