Add blitz feature for Dioxus Native rendering support

Add an orthogonal `blitz` feature flag that switches the rendering
framework from dioxus webview to dioxus-native (Blitz). Can be combined
with `desktop` or `mobile` features. Also bumps rfd to ^0.17.0 (upstream
git moved forward), removes stale gui-level [patch.crates-io] section,
and adds xdotool to the Dockerfile for libxdo (blitz-shell dependency).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker/claude.Dockerfile

@@ -0,0 +1,33 @@
+FROM archlinux:latest
+
+# Base system + toolchain deps
+RUN pacman -Sy --noconfirm archlinux-keyring && \
+    pacman-key --init && \
+    pacman-key --populate archlinux && \
+    pacman -Syu --noconfirm && \
+    pacman -S --noconfirm --needed \
+        base-devel git sudo xdotool
+
+# Create non-root build user for AUR
+RUN useradd -m -G wheel -s /bin/bash builder && \
+    echo 'builder ALL=(ALL) NOPASSWD: ALL' > /etc/sudoers.d/builder
+
+USER builder
+WORKDIR /home/builder
+
+# Install yay from AUR
+RUN git clone https://aur.archlinux.org/yay.git /home/builder/yay && \
+    cd /home/builder/yay && \
+    makepkg -si --noconfirm
+
+# Use yay to install claude-code (or claude-code-stable)
+RUN yay -S --noconfirm claude-code
+
+# Optional: switch back to root for cleanup
+USER root
+RUN rm -rf /home/builder/yay && \
+    pacman -Scc --noconfirm
+
+# Default working user/environment
+USER builder
+WORKDIR /home/builder