Initial vibeproxy implementation

Self-contained HTTP/HTTPS/TCP/UDP reverse proxy manager written in Go,
with SQLite storage, a Bootstrap 5 admin UI (Go templates, no JS
framework), and a REST API under /api/v1.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QTXFrNP1imCW7jtfL5SZrw

internal/proxy/responsewriter.go

@@ -0,0 +1,55 @@
+package proxy
+
+import (
+	"bufio"
+	"fmt"
+	"net"
+	"net/http"
+)
+
+// statusRecorder wraps http.ResponseWriter to capture status code and
+// bytes written for logging/metrics, while still supporting hijacking
+// (required for WebSocket upgrades) and flushing (required for streaming
+// responses / SSE).
+type statusRecorder struct {
+	http.ResponseWriter
+	status      int
+	bytes       int64
+	wroteHeader bool
+}
+
+func (w *statusRecorder) WriteHeader(code int) {
+	if w.wroteHeader {
+		return
+	}
+	w.status = code
+	w.wroteHeader = true
+	w.ResponseWriter.WriteHeader(code)
+}
+
+func (w *statusRecorder) Write(b []byte) (int, error) {
+	if !w.wroteHeader {
+		w.WriteHeader(http.StatusOK)
+	}
+	n, err := w.ResponseWriter.Write(b)
+	w.bytes += int64(n)
+	return n, err
+}
+
+func (w *statusRecorder) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	hj, ok := w.ResponseWriter.(http.Hijacker)
+	if !ok {
+		return nil, nil, fmt.Errorf("underlying ResponseWriter does not support hijacking")
+	}
+	// A hijacked WebSocket connection never goes through WriteHeader, so
+	// treat it as a successful 101 for logging purposes.
+	w.status = http.StatusSwitchingProtocols
+	w.wroteHeader = true
+	return hj.Hijack()
+}
+
+func (w *statusRecorder) Flush() {
+	if f, ok := w.ResponseWriter.(http.Flusher); ok {
+		f.Flush()
+	}
+}