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

scripts/build-desktop-linux.sh

@@ -0,0 +1,44 @@
+#!/bin/bash
+# Build Linux desktop packages (deb + rpm) for JellyTau.
+#
+# Produces bundles under src-tauri/target/release/bundle/{deb,rpm}.
+# Runs on the existing Ubuntu builder image. NOTE: Tauri has no pacman bundle
+# target — the Arch package is built separately with makepkg (scripts/build-arch.sh
+# / Dockerfile.arch). `appimage` is also available if you want a portable bundle.
+#
+# Usage:
+#   scripts/build-desktop-linux.sh                 # deb + rpm
+#   BUNDLES="deb,appimage" scripts/build-desktop-linux.sh # subset / add appimage
+#   OUTPUT_DIR=/app/dist scripts/build-desktop-linux.sh   # copy bundles out
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+
+BUNDLES="${BUNDLES:-deb,rpm}"
+
+echo "🐧 Building JellyTau Linux desktop packages"
+echo "==========================================="
+echo "Bundles: $BUNDLES"
+echo ""
+
+bun install --frozen-lockfile 2>/dev/null || bun install
+bun run build
+
+# --bundles overrides tauri.conf.json bundle.targets so this script controls
+# exactly which Linux formats are produced (never NSIS here).
+bun run tauri build --bundles "$BUNDLES"
+
+BUNDLE_ROOT="src-tauri/target/release/bundle"
+echo ""
+echo "✅ Built packages:"
+find "$BUNDLE_ROOT" -maxdepth 2 -type f \
+  \( -name '*.deb' -o -name '*.rpm' -o -name '*.AppImage' \) -print
+
+if [[ -n "${OUTPUT_DIR:-}" ]]; then
+  mkdir -p "$OUTPUT_DIR"
+  find "$BUNDLE_ROOT" -maxdepth 2 -type f \
+    \( -name '*.deb' -o -name '*.rpm' -o -name '*.AppImage' \) \
+    -exec cp -v {} "$OUTPUT_DIR/" \;
+  echo ""
+  echo "📦 Copied bundles to $OUTPUT_DIR"
+fi