feat: add mattermost notification provider

Add comprehensive Mattermost integration as a new notification provider:

## Backend Implementation:
- Add `mattermost` to notificationType enum and database schema
- Create mattermost table with webhookUrl, channel, username fields
- Implement CRUD operations: createMattermostNotification, updateMattermostNotification
- Add API routes: createMattermost, updateMattermost, testMattermostConnection
- Add sendMattermostNotification utility with proper payload formatting

## Frontend Implementation:
- Add MattermostIcon component with provided SVG logo
- Extend notification form with Mattermost schema validation
- Add webhook URL (required), channel and username (optional) form fields
- Integrate test connection functionality
- Add Mattermost to provider selection UI

## Notification Integration:
- Integrate across all notification types:
  - Build success/error notifications
  - Database backup notifications
  - Docker cleanup notifications
  - Dokploy restart notifications
  - Server threshold alerts
- Format messages using Markdown for Mattermost compatibility
- Handle optional channel (#prefix) and username override
- Graceful fallback for empty optional fields

## Features:
- Webhook-based messaging to Mattermost channels
- Optional channel targeting and custom username display
- Consistent formatting with other notification providers
- Full CRUD support with proper validation
- Test connection capability

Closes: Support for Mattermost team communication platform

# Conflicts:
#	apps/dokploy/components/dashboard/settings/notifications/handle-notifications.tsx
#	apps/dokploy/components/icons/notification-icons.tsx
#	apps/dokploy/server/api/routers/notification.ts
#	packages/server/src/db/schema/notification.ts
#	packages/server/src/services/notification.ts
#	packages/server/src/utils/notifications/build-error.ts
#	packages/server/src/utils/notifications/build-success.ts
#	packages/server/src/utils/notifications/database-backup.ts
#	packages/server/src/utils/notifications/docker-cleanup.ts
#	packages/server/src/utils/notifications/dokploy-restart.ts
#	packages/server/src/utils/notifications/server-threshold.ts
#	packages/server/src/utils/notifications/utils.ts

packages/server/src/services/notification.ts

@@ -4,6 +4,7 @@ import {
 	type apiCreateEmail,
 	type apiCreateLark,
 	type apiCreateGotify,
+	type apiCreateMattermost,
 	type apiCreateNtfy,
 	type apiCreateSlack,
 	type apiCreateTelegram,
@@ -11,6 +12,7 @@ import {
 	type apiUpdateEmail,
 	type apiUpdateLark,
 	type apiUpdateGotify,
+	type apiUpdateMattermost,
 	type apiUpdateNtfy,
 	type apiUpdateSlack,
 	type apiUpdateTelegram,
@@ -18,6 +20,7 @@ import {
 	email,
 	lark,
 	gotify,
+	mattermost,
 	notifications,
 	ntfy,
 	slack,
@@ -588,6 +591,7 @@ export const findNotificationById = async (notificationId: string) => {
 			email: true,
 			gotify: true,
 			ntfy: true,
+			mattermost: true,
 			lark: true,
 		},
 	});
@@ -711,3 +715,95 @@ export const updateNotificationById = async (
 
 	return result[0];
 };
+
+export const createMattermostNotification = async (
+	input: typeof apiCreateMattermost._type,
+	organizationId: string,
+) => {
+	await db.transaction(async (tx) => {
+		const newMattermost = await tx
+			.insert(mattermost)
+			.values({
+				webhookUrl: input.webhookUrl,
+				channel: input.channel,
+				username: input.username,
+			})
+			.returning()
+			.then((value) => value[0]);
+
+		if (!newMattermost) {
+			throw new TRPCError({
+				code: "BAD_REQUEST",
+				message: "Error input: Inserting mattermost",
+			});
+		}
+
+		const newDestination = await tx
+			.insert(notifications)
+			.values({
+				mattermostId: newMattermost.mattermostId,
+				name: input.name,
+				appDeploy: input.appDeploy,
+				appBuildError: input.appBuildError,
+				databaseBackup: input.databaseBackup,
+				dokployRestart: input.dokployRestart,
+				dockerCleanup: input.dockerCleanup,
+				notificationType: "mattermost",
+				organizationId: organizationId,
+				serverThreshold: input.serverThreshold,
+			})
+			.returning()
+			.then((value) => value[0]);
+
+		if (!newDestination) {
+			throw new TRPCError({
+				code: "BAD_REQUEST",
+				message: "Error input: Inserting notification",
+			});
+		}
+
+		return newDestination;
+	});
+};
+
+export const updateMattermostNotification = async (
+	input: typeof apiUpdateMattermost._type,
+) => {
+	await db.transaction(async (tx) => {
+		const newDestination = await tx
+			.update(notifications)
+			.set({
+				name: input.name,
+				appDeploy: input.appDeploy,
+				appBuildError: input.appBuildError,
+				databaseBackup: input.databaseBackup,
+				dokployRestart: input.dokployRestart,
+				dockerCleanup: input.dockerCleanup,
+				organizationId: input.organizationId,
+				serverThreshold: input.serverThreshold,
+			})
+			.where(eq(notifications.notificationId, input.notificationId))
+			.returning()
+			.then((value) => value[0]);
+
+		if (!newDestination) {
+			throw new TRPCError({
+				code: "BAD_REQUEST",
+				message: "Error Updating notification",
+			});
+		}
+
+		await tx
+			.update(mattermost)
+			.set({
+				webhookUrl: input.webhookUrl,
+				channel: input.channel,
+				username: input.username,
+			})
+			.where(eq(mattermost.mattermostId, input.mattermostId))
+			.returning()
+			.then((value) => value[0]);
+
+		return newDestination;
+	});
+};