packaging: RPM requires library sonames, so openSUSE can install it (#2205)

PdfCraft's RPM requires Fedora package names: `libxkbcommon`, `(vulkan-loader or libglvnd-egl)`.
openSUSE has no `libxkbcommon`, `vulkan-loader` or `libglvnd-egl` package, so zypper refuses it with
`nothing provides 'libxkbcommon'` (exit 4, which the ArtCraft Launcher shows as "error 4";
storytold/craft-launcher#341). Fixes #1472.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

packaging/linux/nfpm.yaml

@@ -46,9 +46,16 @@ overrides:
       - mesa-vulkan-drivers
       - xdg-desktop-portal
   rpm:
+    # Library sonames rather than package names, so the same requirements resolve on Fedora/RHEL
+    # and openSUSE (which has no libxkbcommon, vulkan-loader or libglvnd-egl package). The glibc
+    # floor names libm because the binaries' GLIBC_2.35 symbols (hypot, hypotf) are libm's: RHEL 9's
+    # glibc 2.34 provides libc.so.6(GLIBC_2.35) through backports, but not this, so it refuses.
     depends:
-      - libxkbcommon
-      - (vulkan-loader or libglvnd-egl)
+      - libc.so.6()(64bit)
+      - libm.so.6(GLIBC_2.35)(64bit)
+      - libgcc_s.so.1()(64bit)
+      - libxkbcommon.so.0()(64bit)
+      - (libvulkan.so.1()(64bit) or libEGL.so.1()(64bit))
     recommends:
       - cups-client
       - libwayland-client