feat(hook): write marked profile blocks and register zsh completion

`netssh hook install` and the setup wizard now write the same marked
`# >>> netssh >>>` block as install.sh and replace unmarked entries of
older versions instead of appending duplicates. Uninstall shares the
legacy patterns with the installer (eval/alias/source variants).

For zsh the block adds ~/.zfunc to fpath and calls compdef, so
completion also works when compinit already ran earlier in .zshrc,
e.g. with oh-my-zsh. The installer reports which completion it set up
per shell and how to reset ~/.zcompdump.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/setup/wizard.go

@@ -193,14 +193,9 @@ func RunWizard(cfg *config.Config) error {
 			fmt.Fprintf(os.Stderr, "Run 'netssh hook install --shell bash|zsh|fish' to activate your alias.\n")
 			return nil
 		}
-		if _, err := hook.Install(profile); err != nil {
+		if _, err := hook.Install(profile, shell); err != nil {
 			return err
 		}
-		if shell != "fish" {
-			if _, err := hook.InstallAliasesSource(profile); err != nil {
-				return err
-			}
-		}
 		fmt.Fprintln(os.Stderr, hook.ReloadNote(profile))
 	}
 	return nil