feat: add docker web image support

.dockerignore

@@ -0,0 +1,25 @@
+# Prevent leaking host-specific caches/paths into the image
+.dockerignore
+.git
+.gitignore
+.idea
+.vscode
+**/.DS_Store
+build/
+.dart_tool/
+.flutter-plugins
+.flutter-plugins-dependencies
+.packages
+pubspec.lock # keep if you want reproducible, comment out to include
+# Flutter/Platform build outputs
+android/
+ios/
+linux/
+macos/
+windows/
+web/.dart_tool/
+# Tests and dev artifacts (optional, not needed in image build stage)
+test/
+integration_test/
+coverage/
+custom_lint.log

Dockerfile

@@ -0,0 +1,39 @@
+## Two-stage build for minimal Flutter web static server (Caddy runtime)
+# Stage 1: Build the Flutter web app
+FROM ghcr.io/cirruslabs/flutter:latest AS build
+
+WORKDIR /app
+
+# Copy pubspec first for better layer caching
+COPY pubspec.* ./
+RUN flutter pub get
+
+# Copy the rest of the project
+COPY . .
+
+# Ensure no host caches leak into the container
+RUN rm -rf .dart_tool build && \
+	flutter pub get && \
+	flutter gen-l10n && \
+	flutter build web --release -O4 --wasm
+
+# Stage 2: Caddy (Alpine) to serve static files with SPA fallback
+FROM caddy:2-alpine AS runtime
+WORKDIR /usr/share/caddy
+# Copy built web assets
+COPY --from=build /app/build/web/ /usr/share/caddy/
+# Write Caddyfile inline (listens on :8080 and SPA fallback)
+RUN cat > /etc/caddy/Caddyfile <<'CADDY'
+{
+	admin off
+}
+
+:8080 {
+	root * /usr/share/caddy
+	encode zstd gzip
+	# SPA fallback: serve index.html if file not found
+	try_files {path} /index.html
+	file_server
+}
+CADDY
+EXPOSE 8080

README.md

@@ -39,13 +39,31 @@ flutter build windows
 flutter pub run msix:create
 ```
 
-For web
+#### web
+
 ```bash
 flutter build web
+# flutter build web --release -O4 --wasm
 ```
 Open the `index.html` file in the `build/web` directory. Remove the `<base href="/">` to ensure proper routing on GitHub Pages.
 
+##### Docker
+
+To build and run a minimal Docker image serving static Flutter web files:
+
+```bash
+# Build the Docker image
+docker build -t pdf_signature .
+
+# Run the container (serves static files on port 8080)
+docker run --rm -p 8080:8080 pdf_signature
+```
+Access your app at [http://localhost:8080](http://localhost:8080)
+
+#### Linux
+
 For Linux
+
 ```bash
 flutter build linux
 cp -r build/linux/x64/release/bundle/ AppDir