feat(build): cross-platform desktop packaging; bump to 0.1.0

Adds Docker-based packaging for Linux desktop (deb/rpm), Arch
(.pkg.tar.zst via makepkg), and Windows. Windows cross-compiles from
Linux via the official Tauri path — the x86_64-pc-windows-msvc target
driven by cargo-xwin — and produces an NSIS installer (nsis via
tauri.conf.json targets, since the CLI rejects --bundles nsis on a Linux
host). Verified end to end: builds jellytau.exe + jellytau_x64-setup.exe.

Unifies everything on one registry builder image (Dockerfile.builder):
Android SDK/NDK, rpm/file, clang(+clang-cl)/lld/llvm/nsis, cargo-xwin and
the msvc target. Packaging tools sit in a trailing layer so tool changes
rebuild in ~1min instead of ~15. Desktop stages are thin FROM
${BUILDER_IMAGE} layers; Arch uses a separate archlinux image.

CLAUDE.md: CI must install no system toolchains — everything lives in the
image. Bumps version 0.0.18 -> 0.1.0 (Windows support + webview audio +
equalizer).

TRACES: UR-003, UR-005 | DR-004

Dockerfile.builder

@@ -1,5 +1,9 @@
 # JellyTau Builder Image
-# Pre-built image with all dependencies for building and testing
+# Pre-built image with all dependencies for building, testing, and packaging:
+#   - Android APK (SDK/NDK), Linux desktop (deb/rpm),
+#   - Windows cross via the official Tauri path: MSVC target + cargo-xwin + NSIS
+# Arch packages build in a separate archlinux image (Dockerfile.arch) since
+# makepkg is Arch-specific.
 # Push to your registry: docker build -f Dockerfile.builder -t gitea.tourolle.paris/dtourolle/jellytau-builder:latest .
 
 FROM ubuntu:24.04
@@ -83,6 +87,34 @@ RUN $ANDROID_HOME/cmdline-tools/latest/bin/sdkmanager --sdk_root=$ANDROID_HOME \
 # Set NDK environment variable
 ENV NDK_HOME=$ANDROID_HOME/ndk/$NDK_VERSION
 
+# ---------------------------------------------------------------------------
+# Desktop packaging tools — kept in a trailing layer ON PURPOSE so that adding
+# or changing a packaging tool doesn't invalidate the expensive apt/rust/Android
+# layers above (a tool tweak becomes a ~1-2 min rebuild, not ~15). Covers Linux
+# (deb/rpm) and Windows cross (MSVC via cargo-xwin + NSIS).
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    # Linux desktop packaging: rpmbuild for the .rpm bundle (deb needs nothing extra)
+    rpm \
+    file \
+    # Windows cross-compile (official Tauri path: MSVC target via cargo-xwin).
+    # clang provides clang-cl, the MSVC-compatible C compiler cc-rs uses to build
+    # C deps (bundled sqlite, ring, ...); lld = linker; llvm = llvm-lib/ar etc;
+    # nsis = installer generator.
+    clang \
+    lld \
+    llvm \
+    nsis \
+    && rm -rf /var/lib/apt/lists/* \
+    # Ubuntu's clang package ships clang but NOT the clang-cl alias that cc-rs
+    # invokes for MSVC targets. clang-cl is the same binary in MSVC-compat mode,
+    # so provide it as a symlink.
+    && ln -sf /usr/bin/clang /usr/local/bin/clang-cl
+
+# Windows rust target + cargo-xwin (downloads the MSVC CRT/SDK at build time).
+RUN . $HOME/.cargo/env && \
+    rustup target add x86_64-pc-windows-msvc && \
+    cargo install --locked cargo-xwin
+
 WORKDIR /app
 
 ENTRYPOINT ["/bin/bash"]