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>

cmd/netssh/main.go

@@ -710,9 +710,11 @@ func hookInstallCmd() *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "install",
 		Short: "Add netssh shell-init to your shell profile",
-		Long: `Appends a single line to your shell profile that runs 'netssh shell-init'
-on every new shell session. shell-init checks whether the cache is older
-than 24 hours and, if so, starts a background refresh — no delay to your prompt.
+		Long: `Adds a marked block (# >>> netssh >>> … # <<< netssh <<<) to your shell
+profile that runs 'netssh shell-init' on every new shell session and, for zsh,
+registers the completion. Unmarked entries from older versions are replaced.
+shell-init checks whether the cache is older than 24 hours and, if so, starts
+a background refresh — no delay to your prompt.
 
 After installation, reload your profile or open a new shell.`,
 		RunE: func(cmd *cobra.Command, args []string) error {
@@ -724,17 +726,12 @@ After installation, reload your profile or open a new shell.`,
 				return err
 			}
 
-			installed, err := hook.Install(profile)
+			// The managed block also sources the aliases (bash/zsh) and registers
+			// zsh completion; fish uses conf.d auto-sourcing instead.
+			installed, err := hook.Install(profile, shell)
 			if err != nil {
 				return err
 			}
-			// For bash/zsh: also add the source line so aliases are loaded on startup.
-			// Fish uses conf.d auto-sourcing — no explicit source line needed.
-			if shell != "fish" {
-				if _, err := hook.InstallAliasesSource(profile); err != nil {
-					return err
-				}
-			}
 
 			if !installed {
 				fmt.Printf("Hook already installed in %s\n", profile)