ci: use conformance repo's composite GitHub Action

Replace custom npx scripts with the composite action from
modelcontextprotocol/conformance. This simplifies the workflow by:

- Removing the manual actions/setup-node step (handled by the action)
- Replacing run-server.sh's npx call with the action
- Replacing the inline npx call for client tests with the action
- Removing continue-on-error (Python SDK passes all tests)

References conformance repo at commit ab789d6 (expected-failures branch)
until a tagged release is available.

Author: maxisbey

.github/workflows/conformance.yml

@@ -16,30 +16,34 @@ permissions:
 jobs:
   server-conformance:
     runs-on: ubuntu-latest
-    continue-on-error: true
     steps:
       - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
       - uses: astral-sh/setup-uv@61cb8a9741eeb8a550a1b8544337180c0fc8476b # v7.2.0
         with:
           enable-cache: true
           version: 0.9.5
-      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
-        with:
-          node-version: 24
       - run: uv sync --frozen --all-extras --package mcp-everything-server
-      - run: ./.github/actions/conformance/run-server.sh
+      - name: Start everything-server
+        run: |
+          uv run --frozen mcp-everything-server --port 3001 &
+          timeout 15 bash -c 'until curl -s http://localhost:3001/mcp > /dev/null 2>&1; do sleep 0.5; done'
+          echo "Server ready"
+      - uses: modelcontextprotocol/conformance@ab789d6f03b7b3561b80a6e835bd07aa8d87c10a
+        with:
+          mode: server
+          url: http://localhost:3001/mcp
 
   client-conformance:
     runs-on: ubuntu-latest
-    continue-on-error: true
     steps:
       - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
       - uses: astral-sh/setup-uv@61cb8a9741eeb8a550a1b8544337180c0fc8476b # v7.2.0
         with:
           enable-cache: true
           version: 0.9.5
-      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
-        with:
-          node-version: 24
       - run: uv sync --frozen --all-extras --package mcp
-      - run: npx @modelcontextprotocol/conformance@0.1.10 client --command 'uv run --frozen python .github/actions/conformance/client.py' --suite all
+      - uses: modelcontextprotocol/conformance@ab789d6f03b7b3561b80a6e835bd07aa8d87c10a
+        with:
+          mode: client
+          command: "uv run --frozen python .github/actions/conformance/client.py"
+          suite: all