ci(docker): add Docker publishing workflow and Dockerfile

Introduce GitHub Actions workflow for automated Docker image
publishing to Docker Hub, along with a dedicated Dockerfile in
the ci directory to streamline container builds.

ci/Dockerfile

@@ -0,0 +1,116 @@
+# =============================================================================
+# Stage 1: Build
+# =============================================================================
+FROM ubuntu:26.04 AS builder
+
+ENV DEBIAN_FRONTEND=noninteractive
+
+# Build dependencies for full build (all features enabled)
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    build-essential \
+    autoconf \
+    automake \
+    autoconf-archive \
+    libtool \
+    pkg-config \
+    git \
+    wget \
+    # Required dependencies
+    libglib2.0-dev \
+    libcurl4-openssl-dev \
+    libsqlite3-dev \
+    libncursesw-dev \
+    libreadline-dev \
+    # Optional: notifications
+    libnotify-dev \
+    # Optional: Python plugins
+    python3-dev \
+    python3 \
+    # Optional: PGP
+    libgpgme-dev \
+    # Optional: OTR
+    libotr-dev \
+    # Optional: GTK icons/clipboard
+    libgtk-3-dev \
+    # Optional: GDK Pixbuf
+    libgdk-pixbuf-2.0-dev \
+    # Optional: OMEMO
+    libsignal-protocol-c-dev \
+    libgcrypt20-dev \
+    # Optional: OMEMO QR code
+    libqrencode-dev \
+    # Optional: xscreensaver
+    libxss-dev \
+    # Test dependencies (needed for build verification)
+    libcmocka-dev \
+    && rm -rf /var/lib/apt/lists/*
+
+# Build libstrophe from source (not available as Ubuntu package)
+RUN git clone --depth 1 https://github.com/strophe/libstrophe.git /tmp/libstrophe \
+    && cd /tmp/libstrophe \
+    && autoreconf -i \
+    && ./configure --prefix=/usr \
+    && make -j$(nproc) \
+    && make install \
+    && rm -rf /tmp/libstrophe
+
+WORKDIR /src
+
+COPY . .
+
+RUN ./bootstrap.sh \
+    && ./configure \
+        --enable-notifications \
+        --enable-icons-and-clipboard \
+        --enable-otr \
+        --enable-pgp \
+        --enable-omemo \
+        --enable-plugins \
+        --enable-c-plugins \
+        --enable-python-plugins \
+        --with-xscreensaver \
+        --enable-omemo-qrcode \
+        --enable-gdk-pixbuf \
+    && make -j$(nproc) \
+    && make install
+
+# =============================================================================
+# Stage 2: Runtime (minimal)
+# =============================================================================
+FROM ubuntu:26.04
+
+ENV DEBIAN_FRONTEND=noninteractive
+
+# Runtime dependencies only (no build tools, no tests)
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    # Required runtime
+    libglib2.0-0 \
+    libcurl4 \
+    libsqlite3-0 \
+    libncursesw6 \
+    libreadline8 \
+    # Optional feature runtimes
+    libnotify4 \
+    python3 \
+    libgpgme11 \
+    libotr5 \
+    libgtk-3-0 \
+    libgdk-pixbuf-2.0-0 \
+    libsignal-protocol-c-2.0.0 \
+    libgcrypt20 \
+    libqrencode4 \
+    libxss1 \
+    ca-certificates \
+    && rm -rf /var/lib/apt/lists/* \
+    && apt-get clean
+
+# Copy installed files from builder stage
+COPY --from=builder /usr/local/bin/profanity /usr/local/bin/profanity
+COPY --from=builder /usr/local/lib/libprofanity* /usr/local/lib/
+COPY --from=builder /usr/local/include/profapi.h /usr/local/include/
+COPY --from=builder /usr/local/share/profanity /usr/local/share/profanity
+
+# Runtime config/data directory
+RUN mkdir -p /root/.config/profanity
+
+ENTRYPOINT ["profanity"]