llvm: drop software-properties-common dep, use deb822 path on trixie (1.1.0)

The llvm.sh script writes the LLVM apt source in deb822 format on
trixie/forky/sid, where add-apt-repository is unavailable (the
software-properties package was removed from trixie). Pre-installing
software-properties-common broke the feature on the new trixie-based
devcontainer base. Drop it; only install what's actually missing from
the rest.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: chapterjason

src/llvm/devcontainer-feature.json

@@ -1,6 +1,6 @@
 {
   "id": "llvm",
-  "version": "1.0.0",
+  "version": "1.1.0",
   "name": "llvm",
   "description": "Installs LLVM / Clang on Debian / Ubuntu via the official apt.llvm.org repository. Major-version binaries (clang, clang++, lld, lldb, clangd, clang-format, clang-tidy, etc.) are symlinked into /usr/local/bin without the version suffix.",
   "documentationURL": "https://github.com/SoureCode/devcontainer-features/tree/master/src/llvm",

src/llvm/install.sh

@@ -6,10 +6,19 @@ set -e
 LLVM_VERSION="${VERSION:-22}"
 LLVM_ALL="${ALL:-true}"
 
-apt-get update
-apt-get install -y --no-install-recommends \
-  ca-certificates curl gnupg lsb-release software-properties-common wget
-rm -rf /var/lib/apt/lists/*
+# llvm.sh writes the LLVM apt source in deb822 format on trixie/forky/sid, so
+# software-properties-common (gone from trixie) is no longer required. Older
+# Debian/Ubuntu suites still need add-apt-repository — install it on demand
+# when llvm.sh asks for it. Only install what's missing.
+NEED=()
+for pkg in ca-certificates curl gnupg lsb-release wget; do
+  dpkg -s "$pkg" >/dev/null 2>&1 || NEED+=("$pkg")
+done
+if [ "${#NEED[@]}" -gt 0 ]; then
+  apt-get update
+  apt-get install -y --no-install-recommends "${NEED[@]}"
+  rm -rf /var/lib/apt/lists/*
+fi
 
 TMPDIR="$(mktemp -d)"
 trap 'rm -rf "$TMPDIR"' EXIT