feat: implement ntfy-discord bridge in Go

- SSE subscription to ntfy with auto-reconnect
- Discord webhook integration with embed formatting
- Priority to color mapping, tag to emoji conversion
- Native HashiCorp Vault support (Kubernetes + token auth)
- Hot reload secrets via fsnotify or Vault polling
- Prometheus metrics (/metrics endpoint)
- Health/ready endpoints for Kubernetes probes
- Comprehensive unit tests and fuzz tests
- Multi-stage Docker build (~10MB scratch image)
- CI/CD pipeline for Gitea Actions

internal/server/server.go

@@ -0,0 +1,93 @@
+package server
+
+import (
+	"context"
+	"encoding/json"
+	"log/slog"
+	"net/http"
+	"time"
+
+	"git.daviestechlabs.io/daviestechlabs/ntfy-discord/internal/bridge"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+// Server provides health and metrics endpoints
+type Server struct {
+	httpServer *http.Server
+	bridge     *bridge.Bridge
+}
+
+// New creates a new HTTP server
+func New(port string, b *bridge.Bridge) *Server {
+	mux := http.NewServeMux()
+
+	s := &Server{
+		bridge: b,
+		httpServer: &http.Server{
+			Addr:         ":" + port,
+			Handler:      mux,
+			ReadTimeout:  5 * time.Second,
+			WriteTimeout: 10 * time.Second,
+		},
+	}
+
+	mux.HandleFunc("/health", s.handleHealth)
+	mux.HandleFunc("/ready", s.handleReady)
+	mux.Handle("/metrics", promhttp.Handler())
+
+	return s
+}
+
+// Start begins serving HTTP requests
+func (s *Server) Start() {
+	slog.Info("starting HTTP server", "addr", s.httpServer.Addr)
+	if err := s.httpServer.ListenAndServe(); err != http.ErrServerClosed {
+		slog.Error("HTTP server error", "error", err)
+	}
+}
+
+// Shutdown gracefully stops the server
+func (s *Server) Shutdown(ctx context.Context) {
+	ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
+	defer cancel()
+
+	if err := s.httpServer.Shutdown(ctx); err != nil {
+		slog.Error("HTTP server shutdown error", "error", err)
+	}
+}
+
+func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
+	status := struct {
+		Status  string `json:"status"`
+		Healthy bool   `json:"healthy"`
+	}{
+		Status:  "ok",
+		Healthy: s.bridge.IsHealthy(),
+	}
+
+	if !status.Healthy {
+		status.Status = "unhealthy"
+		w.WriteHeader(http.StatusServiceUnavailable)
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(status)
+}
+
+func (s *Server) handleReady(w http.ResponseWriter, r *http.Request) {
+	status := struct {
+		Status string `json:"status"`
+		Ready  bool   `json:"ready"`
+	}{
+		Status: "ok",
+		Ready:  s.bridge.IsReady(),
+	}
+
+	if !status.Ready {
+		status.Status = "not ready"
+		w.WriteHeader(http.StatusServiceUnavailable)
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(status)
+}