Release: Flatpak bundles, AppImage zsync updates, README Downloads (#275)

* Release: Flatpak bundles (x86_64, aarch64), AppImage zsync updates, README Downloads

- AppImages embed gh-releases-zsync update information and ship a .zsync beside them;
  the Linux job installs zsync and checks both.
- New flatpak job (x86_64 on ubuntu-24.04, aarch64 on ubuntu-24.04-arm) repackages the
  Linux tarball with packaging/linux/flatpak-bundle.sh and the new bundle manifest, then
  smoke-tests it in the sandbox. finish-args shared with the Flathub manifest (packaging-lint
  checks they match): Wayland/X11, dri, CUPS for printing, Documents and Downloads.
- Only the signing jobs and the draft-release job keep `environment: release`, so a branch
  dispatch is a dry run of everything else and can never draft a release.
- README: a Downloads section listing every build; docs/releasing.md updated.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Flatpak: no CUPS socket (the runtime has no lp); document printing as unavailable there

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Brandon Thomas <shared2@storyteller.ai>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

packaging/linux/flatpak/ai.storyteller.pdfcraft.bundle.yml

@@ -0,0 +1,52 @@
+# Flatpak manifest for the single-file bundle attached to every GitHub release
+# (pdfcraft-<version>-linux-<arch>.flatpak). Build it with packaging/linux/flatpak-bundle.sh.
+#
+# It repackages the release's own Linux tarball (pdfcraft-<version>-linux-<arch>.tar.gz, built on
+# Ubuntu 22.04 by package.sh) instead of compiling Rust inside flatpak-builder: no network and no
+# vendored crate sources during the build, a few seconds instead of 20+ minutes, and byte-for-byte
+# the same binaries as the AppImage/deb/rpm. The script unpacks the tarball into `stage/` next to a
+# copy of this file. The binaries need glibc >= 2.35 and load X11, Wayland, xkbcommon and Vulkan
+# at runtime; the freedesktop runtime has all of them, and the GPU driver comes from its
+# org.freedesktop.Platform.GL extension.
+#
+# ai.storyteller.pdfcraft.yml (same directory) is the from-source manifest for Flathub. Keep
+# runtime-version and finish-args identical in both (packaging-lint checks this).
+id: ai.storyteller.pdfcraft
+runtime: org.freedesktop.Platform
+runtime-version: '25.08'
+sdk: org.freedesktop.Sdk
+command: pdfcraft
+finish-args:
+  # Display: Wayland first; X11 only when no Wayland compositor is running.
+  - --socket=wayland
+  - --socket=fallback-x11
+  # X11 shared memory (MIT-SHM). Without it the X11 fallback is slow or fails.
+  - --share=ipc
+  # GPU access for the wgpu renderer (Vulkan, or GL as a fallback).
+  - --device=dri
+  # Open/Save dialogs go through the file-chooser portal (rfd's xdg-portal backend) and
+  # drag-and-drop through the document portal, so picked files work anywhere without broad
+  # filesystem access. Documents and Downloads, where PDFs usually live, are granted so files
+  # passed by path (the command line, Open Recent, "Save" next to the original) work there.
+  - --filesystem=xdg-documents
+  - --filesystem=xdg-download
+  # Deliberately not granted: network (Flatpak installs update through flatpak, so Help ▸ Check
+  # for updates reports that GitHub is unreachable; the optional --control channel listens on
+  # 127.0.0.1 inside the sandbox) and home/host filesystem access. No CUPS socket either: printing
+  # runs the `lp` command (crates/print), which the freedesktop runtime doesn't ship, so Print
+  # reports that the spooler is unavailable until it goes through the print portal.
+modules:
+  - name: pdfcraft
+    buildsystem: simple
+    build-commands:
+      - install -Dm755 bin/pdfcraft /app/bin/pdfcraft
+      - install -Dm755 bin/pdfcraft-cli /app/bin/pdfcraft-cli
+      - install -Dm644 share/applications/ai.storyteller.pdfcraft.desktop /app/share/applications/ai.storyteller.pdfcraft.desktop
+      - install -Dm644 share/mime/packages/ai.storyteller.pdfcraft.xml /app/share/mime/packages/ai.storyteller.pdfcraft.xml
+      # Already has the release's version and date substituted by package.sh.
+      - install -Dm644 share/metainfo/ai.storyteller.pdfcraft.metainfo.xml /app/share/metainfo/ai.storyteller.pdfcraft.metainfo.xml
+      # Licences, including the embedded craft-fonts' OFL texts.
+      - mkdir -p /app/share/icons /app/share/doc && cp -R share/icons/hicolor /app/share/icons/ && cp -R share/doc/pdfcraft /app/share/doc/
+    sources:
+      - type: dir
+        path: stage

packaging/linux/flatpak/ai.storyteller.pdfcraft.yml

@@ -8,6 +8,8 @@
 #   flatpak run ai.storyteller.pdfcraft
 #
 # For Flathub, replace the `dir` source with a `git` source pinned to a release tag and commit.
+# The single-file .flatpak attached to each release comes from ai.storyteller.pdfcraft.bundle.yml,
+# which repackages the prebuilt release binaries. Keep runtime-version and finish-args identical.
 id: ai.storyteller.pdfcraft
 runtime: org.freedesktop.Platform
 runtime-version: '25.08'
@@ -16,14 +18,24 @@ sdk-extensions:
   - org.freedesktop.Sdk.Extension.rust-stable
 command: pdfcraft
 finish-args:
-  - --share=ipc
+  # Display: Wayland first; X11 only when no Wayland compositor is running.
   - --socket=wayland
   - --socket=fallback-x11
+  # X11 shared memory (MIT-SHM). Without it the X11 fallback is slow or fails.
+  - --share=ipc
+  # GPU access for the wgpu renderer (Vulkan, or GL as a fallback).
   - --device=dri
-  # Open/Save dialogs use the file-chooser portal (rfd), and drag-and-drop uses the document
-  # portal, so broad filesystem access isn't needed. Pictures is granted for opening files by
-  # path from the command line.
-  - --filesystem=xdg-pictures
+  # Open/Save dialogs go through the file-chooser portal (rfd's xdg-portal backend) and
+  # drag-and-drop through the document portal, so picked files work anywhere without broad
+  # filesystem access. Documents and Downloads, where PDFs usually live, are granted so files
+  # passed by path (the command line, Open Recent, "Save" next to the original) work there.
+  - --filesystem=xdg-documents
+  - --filesystem=xdg-download
+  # Deliberately not granted: network (Flatpak installs update through flatpak, so Help ▸ Check
+  # for updates reports that GitHub is unreachable; the optional --control channel listens on
+  # 127.0.0.1 inside the sandbox) and home/host filesystem access. No CUPS socket either: printing
+  # runs the `lp` command (crates/print), which the freedesktop runtime doesn't ship, so Print
+  # reports that the spooler is unavailable until it goes through the print portal.
 build-options:
   append-path: /usr/lib/sdk/rust-stable/bin
 modules: