fix(ci): cp -r instead of cp -al — /opt and /workspace are different filesystems

The hardlink-copy fix landed and immediately broke with:
  cp: cannot create hard link 'node_modules/<file>' to
      '/opt/node_modules_cache/<file>': Invalid cross-device link

GitHub Actions runners mount the workspace volume at /workspace
(overlay-fs layered onto the runner image), and /opt is the runner
image's own filesystem. Cross-filesystem hardlinks aren't supported.

Switch `cp -al` → `cp -r`. Cost: ~5s for ~200 packages of small JS
files vs ~0s for the broken symlink. Still cheaper than the ~15s
`bun install` fallback. Realpath of /workspace/node_modules/<pkg>/...
stays inside /workspace, so bun build's sibling-dep resolution works.

Both evals.yml and evals-periodic.yml updated.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.github/workflows/evals-periodic.yml

@@ -101,14 +101,14 @@ jobs:
             echo "TMPDIR=/home/runner/.cache"
           } >> "$GITHUB_ENV"
 
-      # Hardlink copy (cp -al) instead of symlink: bun build resolves a file's
+      # Recursive copy (cp -r) instead of symlink: bun build resolves a
-      # realpath when looking for sibling deps, which makes a symlinked
+      # file's realpath when looking for sibling deps. See evals.yml for the
-      # /opt/node_modules_cache fail to resolve transitive deps. See
+      # full explanation. cp -al would be faster but /opt and /workspace
-      # evals.yml for the full explanation.
+      # are on different overlay-fs layers, so cross-device hardlink fails.
       - name: Restore deps
         run: |
           if [ -d /opt/node_modules_cache ] && diff -q /opt/node_modules_cache/.package.json package.json >/dev/null 2>&1; then
-            cp -al /opt/node_modules_cache node_modules
+            cp -r /opt/node_modules_cache node_modules
           else
             bun install
           fi

.github/workflows/evals.yml

@@ -110,20 +110,19 @@ jobs:
             echo "TMPDIR=/home/runner/.cache"
           } >> "$GITHUB_ENV"
 
-      # Restore pre-installed node_modules from Docker image via hardlink copy.
+      # Restore pre-installed node_modules from Docker image via recursive
-      # Why hardlinks instead of symlink: bun build (and Node module resolution
+      # copy. Symlink (`ln -s`) breaks bun's module resolution because bun
-      # in general) resolves a file's realpath when walking up to find
+      # resolves a file's realpath when walking up to find node_modules/<dep>;
-      # node_modules/<dep>. With `ln -s /opt/node_modules_cache node_modules`,
+      # from a symlinked path, realpath escapes the workspace and sibling
-      # resolution from inside socks/build/client/socksclient.js walks the
+      # deps no longer resolve. Hardlink copy (`cp -al`) fails because /opt
-      # /opt/node_modules_cache/... realpath, where there is no parent
+      # and /workspace are on different overlay-fs layers ("Invalid
-      # node_modules dir containing smart-buffer/ip-address. With `cp -al`,
+      # cross-device link"). Recursive copy works on every layout. Cost:
-      # each file's realpath is /workspace/node_modules/..., so sibling deps
+      # ~5s for ~200 packages of small JS files vs ~0s for symlink — still
-      # resolve correctly. Speed is comparable to symlink (hardlinks share
+      # vastly cheaper than rerunning `bun install` (network + resolution).
-      # inodes, no actual data copy).
       - name: Restore deps
         run: |
           if [ -d /opt/node_modules_cache ] && diff -q /opt/node_modules_cache/.package.json package.json >/dev/null 2>&1; then
-            cp -al /opt/node_modules_cache node_modules
+            cp -r /opt/node_modules_cache node_modules
           else
             bun install
           fi