Enhance user communication and improve UI components

- Update CLAUDE.md to mandate informal "Du" form for user communication in all UI text and emails.
- Modify LoginForm and RegisterForm components to reflect informal language in validation messages and placeholders.
- Add secure connection indicators in LoginForm for user awareness.
- Update alert component styles for better visual feedback.
- Introduce experimenta company information document for user reference.

CLAUDE.md

@@ -63,6 +63,9 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 - **All code comments MUST be written in English**
 - User-facing content (UI text, emails) should be in German
+- **User communication MUST use informal "Du" form** (not formal "Sie" form)
+  - Examples: "Dein Konto", "Melde dich an", "Bestätige deine E-Mail"
+  - This applies to all UI text, form labels, buttons, messages, and emails
 - Documentation should be in German (PRD, README)
 
 ## Tech Stack
@@ -222,7 +225,7 @@ Ein Playwright MCP Server ist installiert und verfügbar für:
 
 **Wann nutzen:**
 
-- Nach Implementierung neuer UI-Komponenten
+- Nach Implementierung oder Änderung von UI-Komponenten
 - Bei Layout-Anpassungen (besonders mobile vs. desktop)
 - Zum Testen von Formularen und Interaktionen
 - Zur Validierung des gesamten Checkout-Flows
@@ -880,6 +883,8 @@ For complete implementation with all utilities (PKCE generator, Cidaas API clien
 - **PRD:** See `docs/PRD.md` for complete requirements
 - **Tech Stack:** See `docs/TECH_STACK.md` for technology decisions
 - **Architecture:** See `docs/ARCHITECTURE.md` for system design and data flows
+- **experimenta Info:** See `docs/EXPERIMENTA_INFO.md` for company information (address, opening hours, legal links, contact details)
+
 
 ## Deployment