Add CI coverage for ldk-server-mcp

Run MCP-specific formatting, clippy, and crate tests in a dedicated workflow and add a separate job that exercises the MCP e2e sanity suite on Ubuntu.

Co-Authored-By: HAL 9000

Author: tnull

.github/workflows/mcp.yml

@@ -0,0 +1,66 @@
+name: MCP Checks
+
+on: [ push, pull_request ]
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  mcp-unit:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout source code
+        uses: actions/checkout@v6
+
+      - name: Install Rust stable toolchain
+        run: |
+          curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile=minimal --default-toolchain stable
+          rustup override set stable
+          rustup component add rustfmt clippy
+
+      - name: Check formatting
+        run: cargo fmt --all -- --check
+
+      - name: Check MCP crate builds
+        run: cargo check -p ldk-server-mcp
+
+      - name: Run MCP crate tests
+        run: cargo test -p ldk-server-mcp
+
+      - name: Run MCP crate clippy
+        run: cargo clippy -p ldk-server-mcp --all-targets -- -D warnings
+
+  mcp-e2e:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v6
+
+      - name: Enable caching for bitcoind
+        id: cache-bitcoind
+        uses: actions/cache@v5
+        with:
+          path: bin/bitcoind-${{ runner.os }}-${{ runner.arch }}
+          key: bitcoind-${{ runner.os }}-${{ runner.arch }}
+
+      - name: Download bitcoind
+        if: steps.cache-bitcoind.outputs.cache-hit != 'true'
+        run: |
+          source ./scripts/download_bitcoind.sh
+          mkdir -p bin
+          mv "$BITCOIND_EXE" bin/bitcoind-${{ runner.os }}-${{ runner.arch }}
+
+      - name: Set bitcoind environment variable
+        run: echo "BITCOIND_EXE=$( pwd )/bin/bitcoind-${{ runner.os }}-${{ runner.arch }}" >> "$GITHUB_ENV"
+
+      - name: Run MCP end-to-end tests
+        run: cargo test --manifest-path e2e-tests/Cargo.toml mcp --verbose --color=always -- --test-threads=4 --nocapture
+        env:
+          RUST_BACKTRACE: 1
+          BITCOIND_SKIP_DOWNLOAD: 1