lightning: add initial lightning address receive support

[Beerosagos]

Configure the Breez SDK with the LNURL domain and expose the registered Lightning address through the backend and receive screen. If no address exists yet, the backend registers a random username and retries when a candidate becomes unavailable during registration.

This is the first integration step for LNURL receive support. The ability to generate a new random address or choose a custom address will be added in a future commit.

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[Beerosagos]

@CodeRabbit review

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[coderabbitai]

📝 Walkthrough

Walkthrough

This PR adds Lightning address support. The backend generates and registers a lightning address username (adjective+noun+number) via the Breez SDK, exposes it through a new LightningAddress() method, a GET /address HTTP handler, and an event-driven observer notification on address change. It also introduces a devServers flag controlling LNURL domain selection (dev vs prod) in the Lightning constructor and connection config, updating the corresponding call site in backend.go. On the frontend, new API functions fetch and subscribe to the lightning address, which is displayed as a copyable field on the receive screen, with accompanying locale and style additions. Tests cover username generation, address extraction, event notification, and domain selection.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

Warning

Tools execution failed with the following error:

Failed to run tools: 13 INTERNAL: Received RST_STREAM with code 2 (Internal server error)

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@backend/lightning/address.go`:
- Around line 52-109: The core retry and race-handling logic in
ensureLightningAddress is not covered by tests, so make the lightning-address
SDK interactions injectable like sparkStatus to unit test this path. Refactor
Lightning to route GetLightningAddress, CheckLightningAddressAvailable, and
RegisterLightningAddress through function fields or a small interface, then add
tests for the existing-address fast path, retry on unavailable usernames, and
the registration-failure recheck that continues when the username was claimed
concurrently.

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Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: e33ddb04-412f-4adc-856d-afa1daf2a6d7

📥 Commits

Reviewing files that changed from the base of the PR and between e0e0ddc and e21edf0.

📒 Files selected for processing (12)

• backend/backend.go
• backend/lightning/address.go
• backend/lightning/address_test.go
• backend/lightning/address_words.go
• backend/lightning/event.go
• backend/lightning/handlers.go
• backend/lightning/lightning.go
• backend/lightning/lightning_test.go
• frontends/web/src/api/lightning.ts
• frontends/web/src/locales/en/app.json
• frontends/web/src/routes/lightning/receive/receive.module.css
• frontends/web/src/routes/lightning/receive/receive.tsx

[bznein]

backend untested LGTM

I also took a look at the frontend and LGTM but up to you if you want someone else to review

[Beerosagos]

backend untested LGTM

I also took a look at the frontend and LGTM but up to you if you want someone else to review

thanks! Frontend is temporary anyway, I'll merge as is and then we'll need a separate PR to improve the send flow