Require bubblewrap for Linux sandbox source builds

Homebrew 6.0 enables a Bubblewrap-based sandbox for source builds on
Linux and fails with a fatal error when a rootless bwrap is not on PATH,
breaking brew install --build-from-source in CI. Add bubblewrap as a
Linux-only dependency to both formulae so the sandbox has what it needs.

Author: marcqualie

Formula/denvig-alpha.rb

@@ -16,6 +16,13 @@ class DenvigAlpha < Formula
 
   depends_on "node"
 
+  # Homebrew 6.0 enables a Bubblewrap-based sandbox for source builds on Linux and
+  # aborts with a fatal error if a rootless `bwrap` is not on PATH. Install it on Linux
+  # so `brew install --build-from-source` works without HOMEBREW_NO_SANDBOX_LINUX.
+  on_linux do
+    depends_on "bubblewrap"
+  end
+
   # denvig depends on the first-party @denvig/cli and @denvig/sdk packages, which are
   # published in the same release as denvig itself. Homebrew's npm install injects a
   # --min-release-age cooldown that rejects these freshly published deps with an ETARGET

Formula/denvig.rb

@@ -14,6 +14,13 @@ class Denvig < Formula
 
   depends_on "node"
 
+  # Homebrew 6.0 enables a Bubblewrap-based sandbox for source builds on Linux and
+  # aborts with a fatal error if a rootless `bwrap` is not on PATH. Install it on Linux
+  # so `brew install --build-from-source` works without HOMEBREW_NO_SANDBOX_LINUX.
+  on_linux do
+    depends_on "bubblewrap"
+  end
+
   def install
     system "npm", "install", *std_npm_args
     bin.install_symlink libexec.glob("bin/*")