Init with working version

Basic demo for Tally X AutoIxpert integration to showcase setup in
Go due to impossibility of open-sourcing n8n setup.

helper.go

@@ -0,0 +1,91 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"strconv"
+	"time"
+)
+
+const maxRetries = 3
+
+var client = &http.Client{
+	Timeout: 30 * time.Second,
+}
+
+func Do(ctx context.Context, req *http.Request) (*http.Response, error) {
+	return client.Do(req)
+}
+
+func DoWithRateLimitReset(ctx context.Context, req *http.Request) (*http.Response, error) {
+	var getBody func() (io.ReadCloser, error)
+	if req.Body != nil {
+		b, err := io.ReadAll(req.Body)
+		if err != nil {
+			return nil, err
+		}
+		_ = req.Body.Close()
+
+		getBody = func() (io.ReadCloser, error) {
+			return io.NopCloser(bytes.NewReader(b)), nil
+		}
+		req.GetBody = getBody
+		req.Body, _ = getBody()
+	}
+
+	const safety = 250 * time.Millisecond // small buffer to avoid edge timing
+
+	for attempt := 0; attempt <= maxRetries; attempt++ {
+		r := req.Clone(ctx)
+		if getBody != nil {
+			r.Body, _ = getBody()
+		}
+
+		resp, err := client.Do(r)
+		if err != nil {
+			return nil, err
+		}
+
+		if resp.StatusCode != http.StatusTooManyRequests {
+			return resp, nil
+		}
+
+		resetHeader := resp.Header.Get("X-RateLimit-Reset")
+		_ = resp.Body.Close()
+
+		if attempt == maxRetries {
+			return nil, fmt.Errorf("rate limited (429) after %d retries; last reset header=%q", maxRetries, resetHeader)
+		}
+
+		wait, err := waitUntilUnixReset(resetHeader, safety)
+		if err != nil {
+			// If the header is missing/invalid, fall back to a short backoff
+			wait = 2 * time.Second
+		}
+
+		select {
+		case <-time.After(wait):
+		case <-ctx.Done():
+			return nil, ctx.Err()
+		}
+	}
+
+	return nil, fmt.Errorf("unreachable")
+}
+
+func waitUntilUnixReset(h string, safety time.Duration) (time.Duration, error) {
+	secs, err := strconv.ParseInt(h, 10, 64)
+	if err != nil {
+		return 0, err
+	}
+
+	resetAt := time.Unix(secs, 0)
+	wait := time.Until(resetAt) + safety
+	if wait < 0 {
+		wait = 0
+	}
+	return wait, nil
+}