fixed flatpak embedded psql forgotten dependency

packaging/flatpak/README.md

@@ -8,7 +8,8 @@ unchanged.
 The build uses the official Flatpak Rust and Node SDK extensions. Cargo and
 Yarn resolve the committed lockfiles inside the build sandbox with network
 access. The PostgreSQL 17.10.0 archive, Typst 0.13.1 binary and protoc 21.12
-binary are downloaded by `flatpak-builder` as checksum-pinned sources.
+binary are downloaded by `flatpak-builder` as checksum-pinned sources. A
+compatible libxml2 ABI is included for the embedded PostgreSQL binaries.
 
 ## Build
 

packaging/flatpak/com.kompac.client.yml

@@ -115,3 +115,28 @@ modules:
     cleanup:
       - /bin/protoc
       - /include
+
+  - name: libxml2-compat
+    buildsystem: autotools
+    config-opts:
+      - --without-icu
+      - --without-lzma
+      - --without-python
+      - --without-readline
+    sources:
+      - type: archive
+        url: https://download.gnome.org/sources/libxml2/2.13/libxml2-2.13.9.tar.xz
+        sha256: a2c9ae7b770da34860050c309f903221c67830c86e4a7e760692b803df95143a
+    post-install:
+      - install -Dm644 Copyright /app/share/licenses/libxml2/Copyright
+    cleanup:
+      - /bin
+      - /include
+      - /lib/cmake
+      - /lib/libxml2.a
+      - /lib/libxml2.la
+      - /lib/libxml2.so
+      - /lib/pkgconfig
+      - /share/aclocal
+      - /share/doc
+      - /share/man