feat(packaging): the trial's Linux column and the Linux packages (P11a steps 1 and 3)

The Linux half of the packaging trial, run on this machine and in Debian,
Fedora and Arch containers, and the recipes it produced (docs/packaging.md
holds the table and what it found):

- mise.toml pins cargo-packager 0.11.8 and cargo-generate-rpm 0.21.1, now
  that `just package-linux` calls them. cargo-packager-updater is a
  library, not a tool, so it is not pinned (update.rs does the checking
  with minisign-verify, which is what the updater uses).
- deploy/packaging/: packager.toml (.deb, AppImage, the pacman tarball and
  its PKGBUILD), the rpm table in crates/ledger-cli/Cargo.toml, the AUR's
  own PKGBUILD (repacks the release tarball), build-linux.sh,
  repo-indexes.sh (the apt and dnf indexes, unsigned until the signing
  step), local-release.sh (a throwaway-keyed feed to try `update`),
  test-linux-packages.sh (linux_packages_install_and_upgrade: install
  0.1.0, open books as an ordinary user, upgrade to 0.1.1, check the host
  restarted onto the new file, the books' last journal line unchanged and
  `update` refuses; passes on Debian trixie, Fedora and Arch). A package
  marks itself package-managed with share/wanderbooks/install-method.
- The icon is a placeholder square (the AppImage cannot be built without
  one).
- .github/workflows/release.yml: on a version tag, build on ubuntu-24.04
  (the oldest glibc the packages claim: a program linked on this machine
  needs GLIBC_2.43 and does not start on Debian 13), attach the packages to
  the release, and add them to the apt and dnf repositories on gh-pages.
  No signing and no macOS or Windows job yet.
- The release profile strips symbols.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp

deploy/README.md

@@ -32,8 +32,10 @@ sudo install -D -m 0644 deploy/wanderbooks-server.service \
 ```
 
 The executable is the server-only build: no viewer, no window libraries.
-On a Linux package install (P11) this is the same binary and the package
-manager writes the file; until then, copy it as above.
+The Linux packages (`.deb`, `.rpm`, AUR; `just package-linux`, docs/packaging.md)
+carry the viewer build, which also serves: on a package install the package
+manager writes the file and `wanderbooks update` refuses. A server with no
+window libraries is still this server-only build, copied as above.
 
 ## 2. Make the data root, once