Document GTK4 blocker in README and devel-setup.sh

Tauri v2's Linux backend hard-depends on GTK3 + webkit2gtk-4.1; GTK4
support is tracked upstream (tauri#7335, tao#1104, wry#1228) but
unmerged with no ETA. Note this so it isn't re-investigated from
scratch later.

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

README.md

@@ -31,6 +31,14 @@ Both default to the OS app-data dir (e.g. `~/.local/share/com.garrettmills.mtgc/
 npm install                  # frontend deps
 ```
 
+> **Why GTK3, not GTK4?** Tauri v2's Linux backend (`wry`/`tao`) hard-depends on
+> GTK3 + `webkit2gtk-4.1`; there's no GTK4/webkitgtk-6.0 option yet. GTK4 support is
+> tracked upstream but unmerged with no ETA:
+> [tauri#7335](https://github.com/tauri-apps/tauri/issues/7335),
+> [tao#1104](https://github.com/tauri-apps/tao/pull/1104),
+> [wry#1228](https://github.com/tauri-apps/wry/issues/1228). Revisit once Tauri
+> ships GTK4 support (likely Tauri v3).
+
 ## Run
 
 ```bash
@@ -63,24 +71,19 @@ Outputs (under the workspace `target/release/`):
   libraries (`webkit2gtk4.1`, `gtk3`), so those must be present on the machine that
   runs it — they are on any modern desktop Linux and are installed by
   `devel-setup.sh`.
-- **`target/release/bundle/appimage/*.AppImage`** — a single portable file that
-  bundles the app together with its runtime. This is the closest thing to a
-  download-and-run **single self-contained binary**: `chmod +x` it and run.
-  **Recommended** for copying to another machine.
 - **`target/release/bundle/rpm/*.rpm`** and **`.../deb/*.deb`** — native installers
   (Fedora / Debian-based) that add a menu entry and icon.
 
 Useful variants:
 
 ```bash
-cargo tauri build --bundles appimage   # only the portable AppImage, skip installers
 cargo tauri build --no-bundle          # only the bare target/release/mtgc-app binary
 ```
 
 Notes:
 
-- On Linux the truly portable single file is the **AppImage**; the bare `mtgc-app`
-  binary is also a single file but relies on the system WebKit/GTK libs.
+- The `mtgc-app` binary is a single file but relies on the system WebKit/GTK libs
+  being present (installed by `devel-setup.sh`).
 - The binary does **not** embed card data — first run still downloads the Scryfall
   bulk into the OS app-data dir, and your synced `library.db` lives there by default
   (override with *Choose library file…*).

scripts/devel-setup.sh

@@ -33,6 +33,11 @@ else
 fi
 
 # --- 2. Tauri v2 system libraries (Fedora / dnf) ---------------------------
+#
+# These are GTK3 packages by necessity, not choice: Tauri v2's Linux backend
+# (wry/tao) hard-depends on GTK3 + webkit2gtk-4.1. GTK4 support is tracked
+# upstream but unmerged with no ETA — see the README's "Why GTK3, not GTK4?"
+# note (tauri#7335, tao#1104, wry#1228) before "fixing" this in isolation.
 
 FEDORA_PKGS=(
     webkit2gtk4.1-devel