Bundle non-system libraries instead of version-pinning depends

Bundling R alone was not enough: R links libicuuc, and Arch moves ICU
regularly. The obvious fix - pinning 'icu>=78 <79' in depends - is worse
than the disease on a rolling distro, because pacman would then refuse to
upgrade ICU while JASP is installed, blocking the user's whole system
upgrade until a rebuild lands.

So bundle-libs.sh copies every non-system shared library into
/opt/jasp-desktop/lib and rewrites rpaths, by denylist rather than
allowlist. depends now carries no version constraints at all.

Qt6 stays system-provided on purpose - Qt is binary compatible across Qt 6
minors, and bundling QtWebEngine would add ~500 MB. That also means the
only rebuild triggers left are a new JASP release and a Qt major bump;
rebuilding for anything else would cost users a 1.7 GB re-download.

Also fixes check-upstream.py querying only repo=Extra, which silently
returned nothing for icu (it lives in core).

scripts/gen-pkgbuild.py

@@ -64,17 +64,12 @@ def main() -> int:
     )
 
     qt_minor = info["qt6_minor"]
-    icu_major = info["icu_major"]
 
     substitutions = {
         "@MAINTAINER@": args.maintainer,
         "@JASP_VERSION@": jasp_version,
         "@PKGREL@": str(pkgrel),
         "@BUNDLED_R@": info["bundled_r_version"],
-        "@QT_MINOR@": qt_minor,
-        "@QT_NEXT_MINOR@": next_minor(qt_minor),
-        "@ICU_MAJOR@": icu_major,
-        "@ICU_NEXT_MAJOR@": str(int(icu_major) + 1),
         "@DOWNLOAD_URL@": download_url,
         "@SHA256@": info["sha256"],
     }
@@ -96,9 +91,8 @@ def main() -> int:
         json.dump({"tag": tag, "pkgrel": pkgrel, "download_url": download_url, **info}, fh, indent=2)
 
     print(f"wrote {args.out} ({args.pkgname} {jasp_version}-{pkgrel})")
-    print(f"  R   bundled at {info['bundled_r_version']} (not an Arch dependency)")
-    print(f"  Qt  pinned to >={qt_minor} <{next_minor(qt_minor)}")
-    print(f"  ICU pinned to >={icu_major} <{int(icu_major) + 1}")
+    print(f"  R bundled at {info['bundled_r_version']}; built against Qt {qt_minor}")
+    print("  depends are unpinned - everything volatile is bundled")
     return 0