split hivectl main.rs into per-domain modules (#2509)

hivectl/src/completions.rs

@@ -0,0 +1,14 @@
+//! `hivectl completions <shell>` — emit a shell completion script,
+//! generated from the live clap command tree so it never drifts from the
+//! actual verbs and flags.
+
+use crate::cli::Cli;
+
+/// Emit a shell completion script for `hivectl` to stdout. Walks the clap
+/// command tree (the single source of truth — same tree `markdown-docs`
+/// renders) so completions never drift from the actual verbs/flags.
+pub(crate) fn generate_completions(shell: clap_complete::Shell) {
+    use clap::CommandFactory as _;
+    let mut cmd = Cli::command();
+    clap_complete::generate(shell, &mut cmd, "hivectl", &mut std::io::stdout());
+}