fix(ci): disable Corepack network access in workflows

- Add COREPACK_ENABLE_NETWORK: 0 to all workflow jobs
- Prevents network access during package manager operations

Fixes build issues with Corepack network access in CI.

refs #17

Author: wishket-pjw

.github/workflows/canary.yml

@@ -23,6 +23,8 @@ jobs:
   publish-canary:
     if: github.repository == 'JeremyDev87/codingbuddy'
     runs-on: ubuntu-latest
+    env:
+      COREPACK_ENABLE_NETWORK: 0
     defaults:
       run:
         working-directory: mcp-server

.github/workflows/dev.yml

@@ -23,6 +23,8 @@ jobs:
   publish-dev:
     if: github.repository == 'JeremyDev87/codingbuddy'
     runs-on: ubuntu-latest
+    env:
+      COREPACK_ENABLE_NETWORK: 0
     defaults:
       run:
         working-directory: mcp-server

.github/workflows/release.yml

@@ -14,6 +14,8 @@ defaults:
 jobs:
   publish:
     runs-on: ubuntu-latest
+    env:
+      COREPACK_ENABLE_NETWORK: 0
     steps:
       - name: Checkout code
         uses: actions/checkout@v4

.yarn/releases/yarn-4.11.0.cjs

@@ -0,0 +1 @@
+yarnPath: .yarn/releases/yarn-4.11.0.cjs