fix(ci): add verification step for downloaded build artifacts

Add explicit verification that bootstrap and dependency artifacts were
successfully downloaded before proceeding with builds. This will catch
artifact download issues early with clear error messages.

Verification steps check:
- build-smol.yml: bootstrap-smol.js (required by smol builder)
- build-sea.yml: bootstrap-npm.js, socket/dist, cli/dist (required by SEA)

If artifacts are missing, build fails immediately with descriptive error
instead of failing later with cryptic MODULE_NOT_FOUND errors.

Related to previous fix (1d8f676) which made bootstrap copy failures
explicit in the build script.

Author: jdalton

.github/workflows/build-sea.yml

@@ -139,6 +139,30 @@ jobs:
           name: build-deps-${{ github.sha }}
           path: packages/
 
+      - name: Verify build artifacts
+        shell: bash
+        run: |
+          echo "=== Verifying downloaded build artifacts ==="
+          ls -lh packages/bootstrap/dist/ || echo "⚠️  bootstrap/dist/ not found"
+          ls -lh packages/socket/dist/ || echo "⚠️  socket/dist/ not found"
+          ls -lh packages/cli/dist/ || echo "⚠️  cli/dist/ not found"
+
+          # Check critical files
+          if [ ! -f packages/bootstrap/dist/bootstrap-npm.js ]; then
+            echo "❌ ERROR: bootstrap-npm.js not found!"
+            exit 1
+          fi
+          if [ ! -f packages/socket/dist/index.mjs ]; then
+            echo "❌ ERROR: socket package not built!"
+            exit 1
+          fi
+          if [ ! -f packages/cli/dist/cli.mjs ]; then
+            echo "❌ ERROR: CLI not built!"
+            exit 1
+          fi
+
+          echo "✓ Build artifacts verified"
+
       - name: Setup Node.js
         uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5.0.0
         with:

.github/workflows/build-smol.yml

@@ -131,6 +131,21 @@ jobs:
           name: build-deps-smol-${{ github.sha }}
           path: packages/
 
+      - name: Verify bootstrap artifacts
+        shell: bash
+        run: |
+          echo "=== Verifying downloaded bootstrap artifacts ==="
+          ls -lh packages/bootstrap/dist/ || echo "⚠️  bootstrap/dist/ not found"
+          ls -lh packages/socket/dist/ || echo "⚠️  socket/dist/ not found"
+
+          if [ ! -f packages/bootstrap/dist/bootstrap-smol.js ]; then
+            echo "❌ ERROR: bootstrap-smol.js not found!"
+            echo "This file is required by the smol builder."
+            exit 1
+          fi
+
+          echo "✓ Bootstrap artifacts verified"
+
       - name: Setup Node.js
         uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5.0.0
         with: