Fix Dockerfile conflict markers broken on main (#3)

* Fix conflict markers on main and guard CI against them

PR #2 merged before the Dockerfile cleanup landed, leaving <<<<<<<
markers that break docker compose build. Restore clean Docker files
and fail CI if conflict markers appear in the tree.

* Add CI check that fails on merge conflict markers

* Narrow conflict-marker CI check to <<<<<<< and >>>>>>>

---------

Co-authored-by: Cursor Agent <[email protected]>

.github/workflows/ci.yml

@@ -10,6 +10,16 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
+
+      - name: Reject merge conflict markers
+        run: |
+          if git grep -nE '^(<<<<<<<|>>>>>>>)' -- . \
+            ':(exclude)package-lock.json'; then
+            echo "::error::Merge conflict markers found in tracked files"
+            exit 1
+          fi
+          echo "No conflict markers found"
+
       - uses: actions/setup-node@v4
         with:
           node-version: "22"