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/api/json.go

@@ -0,0 +1,63 @@
+// Package api implements the REST API under /api/v1, authenticated with
+// bearer API tokens (separate from the web UI's Basic Auth).
+package api
+
+import (
+	"database/sql"
+	"encoding/json"
+	"net/http"
+	"strconv"
+
+	"github.com/owen/vibeproxy/internal/auth"
+	"github.com/owen/vibeproxy/internal/logging"
+)
+
+const maxJSONBody = 10 << 20 // 10 MiB is plenty for config payloads
+
+func writeJSON(w http.ResponseWriter, status int, v any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	json.NewEncoder(w).Encode(v)
+}
+
+func writeError(w http.ResponseWriter, status int, msg string) {
+	writeJSON(w, status, map[string]string{"error": msg})
+}
+
+func decodeJSON(w http.ResponseWriter, r *http.Request, v any) bool {
+	r.Body = http.MaxBytesReader(w, r.Body, maxJSONBody)
+	dec := json.NewDecoder(r.Body)
+	dec.DisallowUnknownFields()
+	if err := dec.Decode(v); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid request body: "+err.Error())
+		return false
+	}
+	return true
+}
+
+func pathID(r *http.Request) (int64, error) {
+	return strconv.ParseInt(r.PathValue("id"), 10, 64)
+}
+
+func audit(db *sql.DB, r *http.Request, action, target, details string) {
+	logging.Audit(db, auth.ActorFromContext(r.Context()), action, target, details)
+}
+
+func queryInt(r *http.Request, key string, def int) int {
+	v := r.URL.Query().Get(key)
+	if v == "" {
+		return def
+	}
+	n, err := strconv.Atoi(v)
+	if err != nil {
+		return def
+	}
+	return n
+}
+
+func nilIfEmptyID(id int64) *int64 {
+	if id == 0 {
+		return nil
+	}
+	return &id
+}