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/core/templates/core/index.html

@@ -547,6 +547,20 @@
           </div>
           <div class="col q-pl-md"></div>
         </div>
+        <div class="row">
+          <div class="col">
+            <a
+              href="https://nwc.dev/"
+              target="_blank"
+              rel="noopener noreferrer"
+            >
+              <q-img
+                contain
+                :src="($q.dark.isActive) ? '{{ static_url_for('static', 'images/nwc.png') }}' : '{{ static_url_for('static', 'images/nwcl.png') }}'"
+              ></q-img>
+            </a>
+          </div>
+        </div>
       </div>
     </div>
   </div>