✨ feat(matrix-bots): add i18n system and direct message fallback

- Add I18nService with per-user language preferences (de/en)
- Add !language/!sprache command to all 4 bots (todo, calendar, contacts, clock)
- Add fallback behavior: messages without commands create tasks/events/contacts/timers
- Improve clock bot duration parsing to accept bare numbers as minutes (e.g. "25" = 25min)
- Add support for more duration formats: "25 minuten", "1 stunde", etc.

Language preferences stored in SessionService, default configurable via BOT_DEFAULT_LANGUAGE env var.

services/matrix-contacts-bot/src/bot/bot.module.ts

@@ -1,7 +1,12 @@
 import { Module } from '@nestjs/common';
 import { MatrixService } from './matrix.service';
 import { ContactsModule } from '../contacts/contacts.module';
-import { SessionModule, TranscriptionModule, CreditModule } from '@manacore/bot-services';
+import {
+	SessionModule,
+	TranscriptionModule,
+	CreditModule,
+	I18nModule,
+} from '@manacore/bot-services';
 
 @Module({
 	imports: [
@@ -11,6 +16,7 @@ import { SessionModule, TranscriptionModule, CreditModule } from '@manacore/bot-
 			sttUrl: process.env.STT_URL || 'http://localhost:3020',
 		}),
 		CreditModule.forRoot(),
+		I18nModule.forRoot(),
 	],
 	providers: [MatrixService],
 	exports: [MatrixService],

services/matrix-contacts-bot/src/bot/matrix.service.ts

@@ -9,7 +9,14 @@ import {
 	UserListMapper,
 } from '@manacore/matrix-bot-common';
 import { ContactsService, Contact } from '../contacts/contacts.service';
-import { SessionService, TranscriptionService, CreditService } from '@manacore/bot-services';
+import {
+	SessionService,
+	TranscriptionService,
+	CreditService,
+	I18nService,
+	Language,
+	LANGUAGE_NAMES,
+} from '@manacore/bot-services';
 import { HELP_MESSAGE } from '../config/configuration';
 
 const CONTACT_CREATE_CREDITS = 0.02;
@@ -32,7 +39,8 @@ export class MatrixService extends BaseMatrixService {
 		private readonly transcriptionService: TranscriptionService,
 		private contactsService: ContactsService,
 		private sessionService: SessionService,
-		private creditService: CreditService
+		private creditService: CreditService,
+		private i18nService: I18nService
 	) {
 		super(configService);
 	}
@@ -102,6 +110,10 @@ Sag "hilfe" fur alle Befehle!`;
 			await this.handleCommand(roomId, event, sender, `!${detectedCommand}`);
 			return;
 		}
+
+		// Fallback: treat any message as a new contact
+		const args = message.trim().split(/\s+/);
+		await this.handleCreateContact(roomId, event, sender, args);
 	}
 
 	private async handleCommand(
@@ -188,6 +200,12 @@ Sag "hilfe" fur alle Befehle!`;
 				await this.pinHelpMessage(roomId, event);
 				break;
 
+			case 'language':
+			case 'sprache':
+			case 'lang':
+				await this.handleLanguage(roomId, event, sender, argString);
+				break;
+
 			default:
 				await this.sendReply(
 					roomId,
@@ -766,4 +784,47 @@ Sag "hilfe" fur alle Befehle!`;
 			await this.sendReply(roomId, event, 'Fehler beim Pinnen der Hilfe.');
 		}
 	}
+
+	private async handleLanguage(
+		roomId: string,
+		event: MatrixRoomEvent,
+		userId: string,
+		args: string
+	) {
+		const lang = args.trim().toLowerCase();
+
+		if (!lang) {
+			const currentLang = await this.i18nService.getLanguage(userId);
+			const langName = LANGUAGE_NAMES[currentLang];
+			const available = this.i18nService
+				.getAvailableLanguages()
+				.map((l) => `${l} (${LANGUAGE_NAMES[l]})`)
+				.join(', ');
+			await this.sendReply(
+				roomId,
+				event,
+				`**Sprache / Language:** ${langName}\n\n**Verfügbar / Available:** ${available}\n\nÄndern / Change: \`!language de\` oder / or \`!language en\``
+			);
+			return;
+		}
+
+		if (!this.i18nService.isValidLanguage(lang)) {
+			const available = this.i18nService.getAvailableLanguages().join(', ');
+			await this.sendReply(
+				roomId,
+				event,
+				`Unbekannte Sprache / Unknown language: ${lang}\n\nVerfügbar / Available: ${available}`
+			);
+			return;
+		}
+
+		await this.i18nService.setLanguage(userId, lang as Language);
+		const langName = LANGUAGE_NAMES[lang as Language];
+
+		if (lang === 'de') {
+			await this.sendReply(roomId, event, `Sprache geändert zu: **${langName}**`);
+		} else {
+			await this.sendReply(roomId, event, `Language changed to: **${langName}**`);
+		}
+	}
 }