Replace tray-icon with ldtray; make gui default; drop the -server build

ldtray loads every platform toolkit at runtime (libdbus/shell32/AppKit via
libloading) with zero compile-time GUI linkage, so one binary runs on both
desktops and headless servers — on a server Tray::new just returns an
error we ignore and run the worker without a tray. This removes the whole
reason the separate `-server` build existed.

- gui.rs rewritten against ldtray: worker on a background thread, a 1s
  refresher thread rebuilds the menu (via TrayHandle::set_menu) to track
  status, clicks handled in Tray::run on the main thread. ldtray also
  provides desktop notifications, so notify-rust is gone too. Menu, GPU
  list, pause/resume, and update-check feedback are unchanged in behavior.
- gui is now a default feature; the only shipped build carries the tray.
  --no-default-features still yields a pure worker binary.
- Deps: drop tray-icon, gtk, glib, windows-sys, notify-rust; add ldtray.
  CI drops the GTK/libxdo/appindicator apt install (nothing linked at
  build time) and the build-server job; build is now plain --release.
- Auto-updater un-gated from the gui feature (the gating was a
  -server artifact): a single update stream for the single build.

Both feature configs build/clippy/test/doc clean; ldtray tray verified
live on Linux (worker claims + runs). Bump to 0.1.17.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: MagicalTux

.github/workflows/build.yml

@@ -39,15 +39,8 @@ jobs:
 
       - uses: Swatinem/rust-cache@v2
 
-      # The `gui` feature builds the system-tray UI. On Linux that needs GTK 3,
-      # libxdo (cursor/X11 helper used by tray-icon) and an AppIndicator dev
-      # package; Windows links these from the OS, so no extra packages there.
-      - name: Install GUI build deps (Linux)
-        if: runner.os == 'Linux'
-        run: |
-          sudo apt-get update
-          sudo apt-get install -y --no-install-recommends \
-            libgtk-3-dev libxdo-dev libayatana-appindicator3-dev
+      # No GUI system packages needed: the `gui` feature uses ldtray, which loads
+      # every platform toolkit at runtime — nothing is linked at build time.
 
       # Provides the link-time CUDA driver library: the libcuda.so stub on Linux and
       # cuda.lib on Windows. The runtime libcuda is the NVIDIA driver on the volunteer
@@ -60,8 +53,9 @@ jobs:
           cuda: "12.6.0"
 
       - name: Build
-        # Release binaries ship the system-tray GUI by default.
-        run: cargo build --release --locked --features gui
+        # The `gui` feature (ldtray tray) is on by default; the one binary runs on
+        # both desktops and headless servers.
+        run: cargo build --release --locked
 
       - name: Package (Linux → tar.gz)
         if: runner.os == 'Linux'
@@ -90,41 +84,3 @@ jobs:
           name: ${{ matrix.target }}
           path: target/release/${{ matrix.bin }}
           if-no-files-found: error
-
-  # Headless console build for servers: no GUI/tray, and — by design — no
-  # auto-updater (the `master` update channel carries the GTK-linked GUI binary,
-  # which won't start on a headless box). Shipped as a download-only release asset;
-  # operators upgrade by re-downloading. Only the .tar.gz is uploaded (no
-  # triple-named raw binary), so `rsupd publish --ci` never stages it into the
-  # signed update package.
-  build-server:
-    name: linux-x86_64-server
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-
-      - uses: dtolnay/rust-toolchain@stable
-
-      - uses: Swatinem/rust-cache@v2
-
-      # build.rs links libcuda regardless of the GUI feature, so the CUDA toolkit
-      # is still needed to resolve the driver symbols at link time.
-      - name: Install CUDA toolkit
-        uses: Jimver/cuda-toolkit@v0.2.35
-        id: cuda
-        with:
-          cuda: "12.6.0"
-
-      - name: Build (console, no GUI)
-        run: cargo build --release --locked
-
-      - name: Package (→ tar.gz)
-        run: |
-          mkdir -p dist
-          tar -czf "dist/decryptd-linux-x86_64-server.tar.gz" -C target/release decryptd
-
-      - uses: actions/upload-artifact@v4
-        with:
-          name: decryptd-linux-x86_64-server.tar.gz
-          path: dist/decryptd-linux-x86_64-server.tar.gz
-          if-no-files-found: error