Match vmic's custom top-level --help renderer

Ports vmic's print_full_help (main.rs) verbatim in spirit: one line per
subcommand with its positional args inline, an indented per-flag block
underneath with globally-aligned columns, a separate Aliases section, and
NO_COLOR-aware coloring - so `porthole`/`porthole -h`/`porthole help` show
every subcommand's flags without drilling into each one's own --help,
matching vmic's actual rendered output exactly in structure.

Also shortened --via's clap value_name from the full grammar
([user@]host[:port][,...]) to HOPS - the long form blew out the column
alignment for every other flag's help text; the full grammar is still in
the flag's help string itself.

Dropped vmic's MULTI_CHAR_ALIASES workaround (for short flags like -sv
that clap can't express natively) since porthole has no multi-char short
flags today - add it back if one shows up.

src/ui.rs

@@ -38,6 +38,10 @@ pub fn blue(s: &str) -> String {
     paint("34", s)
 }
 
+pub fn cyan(s: &str) -> String {
+    paint("36", s)
+}
+
 pub fn err(msg: &str) {
     eprintln!("{}", red(&format!("Error: {msg}")));
 }