Per-distro packaging: .deb / .rpm / AppImage + CI (1.8)

Ships beyond the Arch PKGBUILD so non-Arch users can install without a
Rust toolchain.

## Package metadata (Cargo.toml)

- [package.metadata.deb] for cargo-deb: declares the runtime subprocess
  deps (yt-dlp, ffmpeg, mpv, xdg-utils) that auto-detection can't find,
  plus libxcb1/libc6 link deps and libnotify4 as recommended.
- [package.metadata.generate-rpm] for cargo-generate-rpm with the
  RPM-distro dep names.
- Filled in license / repository / authors / readme package fields.

## scripts/package.sh

One entry point: `scripts/package.sh [deb|rpm|appimage|all]`. Builds the
release binary once and reuses it. Installs cargo-deb / cargo-generate-rpm
on demand; downloads appimagetool to dist/tools/ on first AppImage build.
Per-format failures are isolated and summarized at the end rather than
aborting the run. Output to dist/ (gitignored).

AppImage is hand-rolled (AppDir + AppRun + root desktop/icon) and bundles
only the GUI binary's shared-lib closure — yt-dlp/ffmpeg/mpv stay host
PATH deps, same as the package declarations.

## CI

.forgejo/workflows/release.yml builds all formats on a v* tag push and
attaches them to the Codeberg release via actions/forgejo-release. Manual
workflow_dispatch builds without uploading for smoke testing. Sets
APPIMAGE_EXTRACT_AND_RUN since CI containers lack FUSE.

## docs/PACKAGING.md

Per-format build + install instructions, the Arch PKGBUILD pointer, and
an honest Windows/macOS section: both are blocked on the Linux-only tray
(ksni) + file-picker (rfd xdg-portal) deps needing per-OS abstraction.
The rest of the stack already cross-compiles.

Verified .deb (dpkg control + payload correct) and .rpm (payload correct)
build cleanly through the script on this host.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.forgejo/workflows/release.yml

@@ -0,0 +1,84 @@
+# Build Linux packages and attach them to the Codeberg release when a
+# version tag (v*) is pushed.
+#
+# Codeberg runs Forgejo Actions, which is GitHub-Actions-compatible. The
+# heavy lifting is in scripts/package.sh — this workflow just provisions
+# a build environment, runs it, and uploads the artifacts.
+#
+# Manual trigger (workflow_dispatch) is included so you can smoke-test the
+# build without cutting a tag; that path builds the packages but skips the
+# release-upload step.
+name: release
+
+on:
+  push:
+    tags:
+      - 'v*'
+  workflow_dispatch:
+
+jobs:
+  packages:
+    runs-on: docker
+    # A Debian-based image gives us dpkg + the build toolchain cargo-deb
+    # expects, and rustup for a pinned toolchain.
+    container:
+      image: rust:1.85-bookworm
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install build dependencies
+        # libxcb + friends are needed to *link* the eframe/winit GUI even
+        # in headless CI. curl + file are used by the packaging script and
+        # appimagetool. rpm provides rpmbuild for cargo-generate-rpm's
+        # payload assembly on a Debian host.
+        run: |
+          apt-get update
+          apt-get install -y --no-install-recommends \
+            libxcb1-dev libxcb-render0-dev libxcb-shape0-dev libxcb-xfixes0-dev \
+            curl file rpm ca-certificates
+
+      - name: Cache cargo registry + build
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: cargo-${{ runner.os }}-${{ hashFiles('Cargo.lock') }}
+
+      - name: Build packages
+        # FUSE isn't available in most CI containers, so tell appimagetool
+        # to extract-and-run instead of mounting. The script downloads
+        # appimagetool itself.
+        env:
+          APPIMAGE_EXTRACT_AND_RUN: '1'
+        run: |
+          chmod +x scripts/package.sh
+          scripts/package.sh all
+
+      - name: List artifacts
+        run: ls -la dist/
+
+      - name: Upload to release
+        # Only attaches to a release when triggered by a tag push. The
+        # forgejo-release action creates the release if it doesn't exist
+        # and uploads every file under dist/.
+        if: startsWith(github.ref, 'refs/tags/v')
+        uses: actions/forgejo-release@v2
+        with:
+          direction: upload
+          url: https://codeberg.org
+          repo: ${{ github.repository }}
+          tag: ${{ github.ref_name }}
+          token: ${{ secrets.RELEASE_TOKEN }}
+          release-dir: dist
+          release-notes: |
+            Automated build for ${{ github.ref_name }}.
+
+            Artifacts:
+            - `.deb` — Debian / Ubuntu / Mint
+            - `.rpm` — Fedora / RHEL / openSUSE
+            - `.AppImage` — any Linux (chmod +x and run)
+
+            Runtime requirements: yt-dlp, ffmpeg, mpv, xdg-utils on PATH.