Initial implementation of latent: film-effects editor + develop-later server

Canvas-based client-side editor (grain, vignette, halation, procedural
light leaks, color-cast presets) plus a small Express/SQLite server for
the two paths that need persistence: instant share links and delayed
"send to develop" links with a randomized reveal time.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Dockerfile

@@ -0,0 +1,25 @@
+FROM node:24-slim
+
+# better-sqlite3 has a native addon with no prebuilt binary for this
+# platform/Node combo yet — build it from source, then drop the toolchain.
+RUN apt-get update -q && apt-get install -y --no-install-recommends python3 make g++ \
+  && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+
+COPY server/package*.json server/
+RUN npm install --prefix server --omit=dev \
+  && apt-get purge -y python3 make g++ && apt-get autoremove -y
+
+COPY server/src/ server/src/
+COPY index.html style.css app.js favicon.svg ./
+
+# Do NOT copy data/ — mutable runtime volume holding the SQLite db and
+# image blobs, would get clobbered on every redeploy if baked in.
+ENV NODE_ENV=production
+ENV PORT=3000
+ENV DATA_DIR=/app/data
+
+EXPOSE 3000
+
+CMD ["node", "server/src/index.js"]