feat(v5): add Inertia app shell with Flux health

Adds v5 routing, middleware, home page rendering, team context sharing,
project model/table support, and Flux health reporting. Installs Flux in
container builds with role-aware s6 services and documents runtime roles.

app/Http/Middleware/V5/EnsureCurrentTeam.php

@@ -0,0 +1,54 @@
+<?php
+
+namespace App\Http\Middleware\V5;
+
+use App\Models\Team;
+use App\Models\User;
+use Closure;
+use Illuminate\Http\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+class EnsureCurrentTeam
+{
+    public function handle(Request $request, Closure $next): Response
+    {
+        /** @var User|null $user */
+        $user = $request->user();
+
+        if (! $user) {
+            return $next($request);
+        }
+
+        $currentTeam = $this->resolveCurrentTeam($user);
+
+        if (! $currentTeam) {
+            abort(403, 'No team available for this user.');
+        }
+
+        session(['currentTeam' => $currentTeam]);
+        $request->attributes->set('v5.currentTeam', $currentTeam);
+
+        return $next($request);
+    }
+
+    private function resolveCurrentTeam(User $user): ?Team
+    {
+        $sessionTeamId = data_get(session('currentTeam'), 'id');
+
+        if ($sessionTeamId) {
+            $sessionTeam = $user->teams()
+                ->select('teams.id', 'teams.name', 'teams.description', 'teams.personal_team')
+                ->whereKey($sessionTeamId)
+                ->first();
+
+            if ($sessionTeam) {
+                return $sessionTeam;
+            }
+        }
+
+        return $user->teams()
+            ->select('teams.id', 'teams.name', 'teams.description', 'teams.personal_team')
+            ->orderBy('teams.id')
+            ->first();
+    }
+}

app/Http/Middleware/V5/HandleInertiaRequests.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace App\Http\Middleware\V5;
+
+use Illuminate\Http\Request;
+use Inertia\Middleware;
+
+class HandleInertiaRequests extends Middleware
+{
+    protected $rootView = 'v5.app';
+
+    public function share(Request $request): array
+    {
+        return [
+            ...parent::share($request),
+            'auth' => [
+                'user' => $request->user() ? [
+                    'id' => $request->user()->id,
+                    'name' => $request->user()->name,
+                    'email' => $request->user()->email,
+                ] : null,
+            ],
+        ];
+    }
+}