fix: tag tests needing fresh sandbox — Windows can't auto-install toolchain in temp dirs

Tests 02, 24, 27, 32 create a fresh MCPP_HOME in a temp dir and
expect mcpp to auto-install a toolchain. On Windows, the xlings
LLVM install into a fresh sandbox fails (no pre-seeded xpkgs).
Tag with `fresh-sandbox` capability (Linux/macOS only for now).

Author: Sunrisepeak

tests/e2e/02_new_build_run.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# requires:
+# requires: fresh-sandbox
 # Single-module hello world: mcpp new → build → run
 set -e
 

tests/e2e/24_git_dependency.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# requires:
+# requires: fresh-sandbox
 # 24_git_dependency.sh — M4 #5: git-based dep clones to ~/.mcpp/git/<hash>/
 # and is treated as a path dep.
 set -e

tests/e2e/27_namespace_dependencies.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# requires:
+# requires: fresh-sandbox
 # Namespaced dependencies: `[dependencies.<ns>] name = { path = "..." }`
 # is parsed correctly and the dep is actually picked up by the build.
 # Also verifies that the legacy `"<ns>.<name>" = "..."` quoted form still

tests/e2e/32_semver_merge.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# requires:
+# requires: fresh-sandbox
 # 32_semver_merge.sh — SemVer merge in the transitive walker:
 #   * Two consumers of the same package with overlapping constraints
 #     (one exact, one range) merge to a single satisfying version

tests/e2e/run_all.sh

@@ -43,7 +43,7 @@ OS="$(uname -s)"
 
 case "$OS" in
     Linux)
-        CAPS+=(elf unix-shell)
+        CAPS+=(elf unix-shell fresh-sandbox)
         command -v g++      &>/dev/null && CAPS+=(gcc)
         command -v patchelf &>/dev/null && CAPS+=(patchelf)
         # musl-gcc: check both system PATH and xlings-managed locations
@@ -58,7 +58,7 @@ case "$OS" in
         fi
         ;;
     Darwin)
-        CAPS+=(unix-shell)
+        CAPS+=(unix-shell fresh-sandbox)
         # macOS g++ is Apple Clang, not real GCC — don't add gcc capability.
         # Tests requiring gcc need actual GNU GCC (modules, gcm.cache, etc.)
         ;;