Fix build hang: commit lockfile and use npm ci

The pipeline hung on `npm install` because no package-lock.json existed,
forcing a full from-scratch dependency resolve on every build. Commit the
resolved lockfile and switch the Dockerfile to `npm ci` for deterministic,
fast installs. Add .dockerignore to keep the build context small.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.dockerignore

@@ -0,0 +1,17 @@
+# Keep the build context small and reproducible.
+**/node_modules
+**/dist
+**/build
+**/.venv
+**/__pycache__
+**/*.pyc
+**/data
+*.sqlite
+*.db
+.git
+.gitea
+.github
+.env
+.env.*
+*.log
+.DS_Store

Dockerfile

@@ -3,7 +3,9 @@ FROM node:18-alpine AS frontend-build
 
 WORKDIR /app/frontend
 COPY frontend/package*.json ./
-RUN npm install --legacy-peer-deps
+# npm ci installs from the committed lockfile: deterministic and far faster
+# than a from-scratch resolve. --prefer-offline avoids redundant registry hits.
+RUN npm ci --legacy-peer-deps --prefer-offline --no-audit --fund=false
 COPY frontend/ ./
 RUN npm run build