Cdk ldk node (#904)

* feat: add LDK Node Lightning backend with comprehensive integration

- Add new cdk-ldk-node crate implementing Lightning backend using LDK Node
- Extend MintPayment trait with start/stop methods for processor lifecycle management
- Add LDK Node configuration support to cdk-mintd with chain source and gossip options
- Enhance mint startup/shutdown to properly manage payment processor lifecycle

---------

Co-authored-by: Erik <78821053+swedishfrenchpress@users.noreply.github.com>

.github/workflows/ci.yml

@@ -112,8 +112,10 @@ jobs:
             -p cdk-lnbits,
             -p cdk-fake-wallet,
             -p cdk-payment-processor,
-            -p cdk-mint-rpc,
+            -p cdk-ldk-node,
+            
             -p cdk-signatory,
+            -p cdk-mint-rpc,
             
             # Binaries
             --bin cdk-cli,

.github/workflows/nutshell_itest.yml

@@ -10,6 +10,16 @@ jobs:
     steps:
       - name: checkout
         uses: actions/checkout@v4
+      - name: Free Disk Space (Ubuntu)
+        uses: jlumbroso/free-disk-space@main
+        with:
+          tool-cache: false
+          android: true
+          dotnet: true
+          haskell: true
+          large-packages: true
+          docker-images: true
+          swap-storage: true
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v17
       - name: Nix Cache
@@ -29,6 +39,16 @@ jobs:
     steps:
       - name: checkout
         uses: actions/checkout@v4
+      - name: Free Disk Space (Ubuntu)
+        uses: jlumbroso/free-disk-space@main
+        with:
+          tool-cache: false
+          android: true
+          dotnet: true
+          haskell: true
+          large-packages: true
+          docker-images: true
+          swap-storage: true
       - name: Pull Nutshell Docker image
         run: docker pull cashubtc/nutshell:latest
       - name: Install Nix