fix: accept lnbits 1.x RFC3339 payment timestamps

[xbuddhi]

Summary

Migrating the backend from Voltage (lnbits 0.x) to Railway (lnbits 1.x) broke the bot's transaction history:

[transactions] Error: json: cannot unmarshal string into Go struct field Payment.time of type int

lnbits 0.x serialises a payment's time as unix seconds; 1.x serialises it as an RFC3339 string. The Go structs decoding those payloads declared time as an integer.

• Adds lnbits.UnixTime, which decodes either form and normalises to unix seconds. Marshalling still emits the number, so the API responses these types are serialised into are unchanged.
• Applies it to Payment.Time and webhook.Webhook.Time.

The webhook payload carries the same field. Nothing had failed there yet only because no deposit had arrived since the migration — a decode error on that path drops the incoming payment notification, so it is worth fixing in the same change.

InvoiceStream also declares time as an int but is never unmarshalled into (the handler proxies raw SSE bytes), so it is left alone.

Test plan

• go build ./...
• go test ./internal/lnbits/...
• Decoding verified against the live instance's real response shape:
  • "2026-09-13T11:42:41.293908+00:00" (1.x, fractional seconds) → 1789299761
  • "2026-09-13T11:42:41Z" → 1789299761
  • 1702411690 (0.x, as in the Voltage export) → unchanged
  • null / "" → 0, no error
  • marshal round-trip still emits a number
• Confirm /transactions renders in Telegram after deploy
• Confirm an incoming deposit notification fires

Note: internal/telegram tests fail at init on a missing config.yaml; this is pre-existing and reproduces identically on a clean main.

🤖 Generated with Claude Code

[coderabbitai]

Important

• 🔍 Trigger review

This repository does not receive automatic reviews because it has fewer than 10 stars.

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: 6814c53f-4b52-40bc-8229-99211b22c810

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}