Puls → Dashboard umbenennen + Projekt-Beschreibung

UI/Routing
- Tab + Route: /puls → /dashboard, Heading „Unternehmens-Puls" → „Dashboard"
- Shortcut: g p → g d (Cheatsheet entsprechend)
- Breadcrumbs, 404-Hinweistext, alle internen Links angepasst

Code-Layout
- apps/web/src/routes/puls.tsx → dashboard.tsx (Komponente DashboardRoute)
- apps/api/src/routers/puls.ts → dashboard.ts (dashboardRouter)
- tRPC-Aufrufe: trpc.puls.* / utils.puls.* → trpc.dashboard.* / utils.dashboard.*
- Auth-Redirects (/api/auth/login, /callback, dev-login) zeigen jetzt auf /dashboard

Projekt-Beschreibung
- Migration 0007_project_description: project.description text (nullable)
- Shared Zod: ProjectSchemas.createProjectInput.description (max 2000, optional)
- Backend: project.create mappt input.description
- Frontend Dialog „Neues Projekt": Textarea (3 Zeilen, optional)
- Projekt-Detail: zeigt Beschreibung als whitespace-pre-wrap unter Subtitle

README
- Routen-Tabelle, Shortcut-Liste, Verzeichnis-Baum, DB-Tabellen, Migration-Range,
  Frontend-Routenliste aktualisiert

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/src/lib/router.tsx

@@ -3,7 +3,7 @@ import { lazy, Suspense } from 'react';
 import { AppShell } from '../components/layout/AppShell';
 import { SkeletonCard } from '../components/ui/SkeletonCard';
 
-const Puls = lazy(() => import('../routes/puls').then((m) => ({ default: m.PulsRoute })));
+const Dashboard = lazy(() => import('../routes/dashboard').then((m) => ({ default: m.DashboardRoute })));
 const Heute = lazy(() =>
   import('../routes/heute').then((m) => ({ default: m.HeuteRoute })),
 );
@@ -33,8 +33,8 @@ const router = createBrowserRouter([
     path: '/',
     element: <AppShell />,
     children: [
-      { index: true, element: withSuspense(<Puls />) },
-      { path: 'puls', element: withSuspense(<Puls />) },
+      { index: true, element: withSuspense(<Dashboard />) },
+      { path: 'dashboard', element: withSuspense(<Dashboard />) },
       { path: 'heute', element: withSuspense(<Heute />) },
       { path: 'reflexion', element: withSuspense(<Reflexion />) },
       { path: 'bereich', element: withSuspense(<Bereich />) },