Add initial project structure with backend and frontend setup

- Created backend structure with Go, including main application logic and API endpoints.
- Added Docker support for both development and production environments.
- Introduced frontend using Nuxt 3 with Tailwind CSS for styling.
- Included configuration files for Docker and environment variables.
- Established basic documentation for contributing, development, and deployment processes.
- Set up .gitignore and .dockerignore files to manage ignored files in the repository.

internal/app/topic.go

@@ -0,0 +1,72 @@
+package app
+
+import "sync"
+
+type topic struct {
+	c  []chan *TileData
+	mu sync.Mutex
+}
+
+func (t *topic) watch(c chan *TileData) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.c = append(t.c, c)
+}
+
+func (t *topic) send(b *TileData) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	for i := 0; i < len(t.c); i++ {
+		select {
+		case t.c[i] <- b:
+		default:
+			close(t.c[i])
+			t.c[i] = t.c[len(t.c)-1]
+			t.c = t.c[:len(t.c)-1]
+		}
+	}
+}
+
+func (t *topic) close() {
+	for _, c := range t.c {
+		close(c)
+	}
+	t.c = t.c[:0]
+}
+
+type Merge struct {
+	From, To int
+	Shift    Coord
+}
+
+type mergeTopic struct {
+	c  []chan *Merge
+	mu sync.Mutex
+}
+
+func (t *mergeTopic) watch(c chan *Merge) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.c = append(t.c, c)
+}
+
+func (t *mergeTopic) send(b *Merge) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	for i := 0; i < len(t.c); i++ {
+		select {
+		case t.c[i] <- b:
+		default:
+			close(t.c[i])
+			t.c[i] = t.c[len(t.c)-1]
+			t.c = t.c[:len(t.c)-1]
+		}
+	}
+}
+
+func (t *mergeTopic) close() {
+	for _, c := range t.c {
+		close(c)
+	}
+	t.c = t.c[:0]
+}