Add fused desktop binaries (win/mac/linux) to the pipeline

Fuse the .love into the official LÖVE 11.5 release artifacts: win-x64
(love.exe concat + dlls), mac-universal (love.app bundle, Info.plist
patched) and linux-x64 (AppImage rebuilt via readelf offset +
unsquashfs/mksquashfs — the AppImage runtime is glibc-linked and
cannot run on the alpine builder). The builder image pre-fetches the
dist files to /opt/love-dist and gains squashfs-tools + binutils.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

README.md

@@ -4,13 +4,13 @@ CI/CD templates for [LÖVE](https://love2d.org) (Love2D/Lua) game
 projects, in the same spirit as [tic80-tools](../tic80-tools).
 
 - `example-makefile.make` — project Makefile: local dev targets
-  (`build`, `love`, `web`, `export`, `watch`, `clean`) plus the
-  Woodpecker pipeline targets (`ci-version`, `ci-export`, `ci-upload`,
-  `ci-update`).
+  (`build`, `love`, `web`, `export`, `binaries`, `watch`, `clean`)
+  plus the Woodpecker pipeline targets (`ci-version`, `ci-export`,
+  `ci-binaries`, `ci-upload`, `ci-update`).
 - `example-woodpecker.yaml` — Woodpecker pipeline: version → export
-  (`.love` package + love.js web build) → upload (scp to the droparea)
-  → update (calls the teletypegames `/update` endpoint with
-  `platform=love`).
+  (`.love` package + love.js web build) → binaries (fused desktop
+  builds) → upload (scp to the droparea) → update (calls the
+  teletypegames `/update` endpoint with `platform=love`).
 - `example-tasks.json` — VS Code `.vscode/tasks.json` with the common
   dev tasks: **Run Löve** (`love .`, default build task,
   `Cmd+Shift+B`), **Build & Run Löve**, **Build .love package** and
@@ -25,16 +25,40 @@ projects, in the same spirit as [tic80-tools](../tic80-tools).
 3. Copy `example-tasks.json` to `.vscode/tasks.json`.
 
 The pipeline uploads `$(PROJECT)-$(VERSION).love.zip`,
-`$(PROJECT)-$(VERSION).html.zip` and the versioned `metadata.json` to
-the droparea, then triggers `/update` twice: once with `platform=love`
-(desktop package) and once with `platform=love-web` (web build).
+`$(PROJECT)-$(VERSION).html.zip`, the versioned `metadata.json` and
+the fused binary zips (`-win-x64.zip`, `-mac-universal.zip`,
+`-linux-x64.zip`) to the droparea, then triggers `/update` twice: once
+with `platform=love` (desktop package) and once with
+`platform=love-web` (web build). The API's `BinaryAttachment` concern
+picks up the `<name>-<version>-<slug>.zip` files automatically and
+registers them as `win_x64` / `mac_universal` / `linux_x64` release
+assets.
+
+## Native (fused) binaries
+
+`make binaries VERSION=x.y` builds desktop packages from the official
+LÖVE $(LOVE_VERSION) release artifacts — no compilation involved:
+
+- **win-x64** — `love.exe` + the `.love` concatenated (the standard
+  LÖVE fusing mechanism), zipped together with the dlls.
+- **mac-universal** — the `.love` dropped into the official
+  `love.app` (a universal x86_64+arm64 bundle), `Info.plist` patched
+  to the project name/identifier. Unsigned — Gatekeeper will warn on
+  first launch.
+- **linux-x64** — the official AppImage taken apart, the `.love`
+  fused into `bin/love`, then reassembled. The AppImage runtime is
+  glibc-linked and cannot be executed on alpine, so the Makefile
+  computes the squashfs offset with `readelf` and repacks with
+  `mksquashfs` instead of running `--appimage-extract`.
 
 ## Builder image
 
 `builder.Dockerfile` bakes the pipeline's export-step dependencies
-(zip/unzip/curl/make + `luac` for the syntax check) into
+(zip/unzip/curl/make + `luac` for the syntax check, squashfs-tools +
+binutils for the AppImage fusing) into
 `git.teletypegames.org/internal/love-builder`, and pre-fetches love.js to
-`/opt/lovejs.zip` — the Makefile uses the cached copy when present
+`/opt/lovejs.zip` plus the official LÖVE dist files to
+`/opt/love-dist/` — the Makefile uses the cached copies when present
 and only falls back to downloading from GitHub outside the image:
 
 ```sh
@@ -43,6 +67,8 @@ docker build --platform linux/amd64 -f builder.Dockerfile \
 docker push git.teletypegames.org/internal/love-builder:latest
 ```
 
-Rebuild the image to pick up a newer love.js snapshot.
+Rebuild the image to pick up a newer love.js snapshot or LÖVE
+release (bump `LOVE_VERSION` in the Dockerfile and the Makefile
+together).
 
 Detailed documentation lives on the wiki: `/development/love`.