🔒 refactor(bots): remove !login command and enforce OIDC-only auth

- Remove !login and !logout commands from all 16+ Matrix bots
- Remove login/logout references from all help/welcome messages
- Disable password login in Synapse (password_config.enabled: false)
- System is now OIDC-only via Mana Core authentication

Users must authenticate via "Sign in with Mana Core" in Element.
Existing bot access tokens remain valid.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

services/matrix-nutriphi-bot/src/config/configuration.ts

@@ -27,7 +27,6 @@ export const HELP_MESSAGE = `**NutriPhi Bot - KI-Ernahrungsassistent**
 
 **Befehle:**
 - \`!help\` - Diese Hilfe anzeigen
-- \`!login email passwort\` - Bei NutriPhi anmelden
 - \`!analyze beschreibung\` - Text analysieren
 - \`!today\` / \`heute\` - Tages-Zusammenfassung
 - \`!week\` / \`woche\` - Wochen-Statistik