Resolve the repository from the invoking directory

A task included from the global mise config runs with the config root as its
working directory - $HOME - rather than the directory the user invoked it from.
Deriving the repository from the current directory therefore failed everywhere
except a project-level include, which defeats the point of installing the task
once and using it in every repository.

mise passes the real directory as MISE_ORIGINAL_CWD, so enter it before
resolving the repository, falling back to the current directory when the task
is run directly rather than through mise.

tasks/ai/sbx

@@ -210,7 +210,19 @@ sandbox_profile_name() {
     printf '%s' "$mapped"
 }
 
+# A task included from the global mise config runs with the config root as its
+# working directory ($HOME), not the directory the user invoked it from, so the
+# repository would otherwise be undiscoverable from anywhere.
+enter_invocation_directory() {
+    local invoked_from="${MISE_ORIGINAL_CWD:-$PWD}"
+
+    cd "$invoked_from" ||
+        die "Could not enter the invoking directory: $invoked_from"
+}
+
 repository_context() {
+    enter_invocation_directory
+
     REPO_ROOT="$(git rev-parse --show-toplevel 2>/dev/null)" ||
         die "This command must be run inside a Git repository."