feat: initial release with 48 Mattermost MCP tools

- 27 base tools: channels, messaging, users, reactions, files, DMs
- Team management: invite/remove users, get stats, list members
- Slash commands: execute /remind, /poll, etc.
- Webhook management: incoming and outgoing webhooks
- System tools: server config, logs, bulk status updates
- Channel admin: create, invite, leave, delete channels
- Read-only mode for safe exploration
- Dual token support (bot + PAT) for enhanced security
- Apache 2.0 licensed

Makefile

@@ -0,0 +1,30 @@
+# Mattermost MCP Server Makefile
+
+.PHONY: build test clean dev lint
+
+BINARY_NAME=mattermost-mcp-server
+VERSION?=$(shell git describe --tags --always --dirty 2>/dev/null || echo "dev")
+BUILD_TIME=$(shell date -u '+%Y-%m-%d_%H:%M:%S')
+LDFLAGS=-ldflags "-X main.Version=$(VERSION)"
+
+build:
+	go build $(LDFLAGS) -o $(BINARY_NAME) .
+
+test:
+	go test -v ./...
+
+clean:
+	rm -f $(BINARY_NAME)
+	go clean
+
+dev:
+	go run . -log-level=debug
+
+lint:
+	golangci-lint run
+
+mod:
+	go mod tidy
+	go mod verify
+
+.DEFAULT_GOAL := build