feat: NWC Funding source #2579 (#2631)

* feat: nwc funding source

* implement paid_invoices_stream, fix for unsettled invoices where settled_at is present but None

* cancel pending_payments_lookup_task on cleanup

* Rename subscription_timeout_task to timeout_task

* ensure preimage is not None

* Improve readability, return failed status on expiration in get_payment_status, ensure result_type is checked after error (some implementations might not set a result_type on error)

* fetch account info when possible

* workaround possible race condition on some nwc service providers, improve performance of fallback by using payment_hash from bolt11 invoice

* fundle

* make format

* fix formatting

* fix C901 `_on_message` is too complex (21 > 16)

* format

* fix lint

* format

* fix tests/wallets/test_nwc_wallets.py:80:11: C901 `run` is too complex (17 > 16)

* fix padding

* fix documentation for _verify_event method

* refactoring and fixes

* Split NWCWallet - NWCConnection

* refactor class methods into helpers

* update bundle

* format

* catch NWCError failure codes

* format and fix

* chore: bundle

* add example

* typos

---------

Co-authored-by: Riccardo Balbo <riccardo0blb@gmail.com>
Co-authored-by: benarc <ben@arc.wales>
Co-authored-by: Pavol Rusnak <pavol@rusnak.io>

lnbits/settings.py

@@ -258,6 +258,10 @@ class LnTipsFundingSource(LNbitsSettings):
     lntips_invoice_key: Optional[str] = Field(default=None)
 
 
+class NWCFundingSource(LNbitsSettings):
+    nwc_pairing_url: Optional[str] = Field(default=None)
+
+
 class BreezSdkFundingSource(LNbitsSettings):
     breez_api_key: Optional[str] = Field(default=None)
     breez_greenlight_seed: Optional[str] = Field(default=None)
@@ -287,6 +291,7 @@ class FundingSourcesSettings(
     OpenNodeFundingSource,
     SparkFundingSource,
     LnTipsFundingSource,
+    NWCFundingSource,
     BreezSdkFundingSource,
 ):
     lnbits_backend_wallet_class: str = Field(default="VoidWallet")
@@ -446,6 +451,7 @@ class SuperUserSettings(LNbitsSettings):
             "PhoenixdWallet",
             "VoidWallet",
             "ZBDWallet",
+            "NWCWallet",
         ]
     )