fix(cli): let --enter press the key it is shorthand for (#581) (#606)

`--enter` is documented as sugar for `--key enter`, but the send dispatch
counted only `args.keys`, so `tty7 send %42 --enter` answered "needs TEXT
... or a --key to press" and pressed nothing. The key list is now built
before the dispatch and the dispatch counts it, so a marked address with
`--enter` and nothing else runs what the pane already has typed, and a
bare `send --enter` presses Enter where the caller sits.

An unmarked id is deliberately left out of that promotion. #567 made the
address slot take bare ids, and `send 83 --key C-c` addressing pane 83 is
fine because `--key` says "press this" and nothing else. `--enter` does
not: `send 2 --enter` reads at least as much like typing 2 into your own
pane and running it, and turning it into a keystroke at pane 2 would be
the silent retarget #567 spent its diff closing. It stays a loud error,
now naming both spellings (`send %83 --enter`, `send %PANE 83 --enter`)
rather than only the typing one.

The reference, the bundled skill reference, `send --help` and the
`--enter` help all said the old thing in slightly different words; they
now say the same thing as each other and as the code.

Co-authored-by: l0ng-ai <24760907+l0ng-ai@users.noreply.github.com>

docs/cli/reference.mdx

@@ -93,15 +93,20 @@ share kept by the *existing* pane. Prints `%NN`. JSON: `{"pane"}`.
 
 ### `tty7 send [%PANE] [TEXT] [--enter] [--key KEY]…`
 
-Types `TEXT` into the pane as keystrokes; `--enter` appends CR. With one
-argument the text is the argument and the pane comes from `$TTY7_PANE` — but a
-lone `%42` (or bare `42`, the shape `pane ls --json` prints) is rejected as a
-missing-text error rather than typed, unless a `--key` gives it something to
-do. A `%` followed by a digit that still doesn't parse (`%3x`) is an address
-error, never text for your own pane — while text that merely starts with `%`
-(`%s/foo/bar/`, `%!sort`) types as given, as does anything unmarked that is not
-a plain number (`3x`, `+5`). To type an address-shaped string, name the pane as
-well: `tty7 send %42 %3x`.
+Types `TEXT` into the pane as keystrokes; `--enter` is shorthand for `--key
+enter` — it appends CR to the text, or presses Enter on its own when there is
+none, so `tty7 send %42 --enter` runs whatever pane 42 already has typed. With
+one argument the text is the argument and the pane comes from `$TTY7_PANE` —
+but a lone `%42` (or bare `42`, the shape `pane ls --json` prints) is rejected
+as a missing-text error rather than typed, unless a `--key` gives it something
+to do. `--enter` is that key only for the `%`-marked spelling: `tty7 send 83
+--enter` is refused, because it reads as much like typing `83` into your own
+pane as like pressing Enter in pane 83, and the error names both ways to say
+which (`send %83 --enter`, `send %PANE 83 --enter`). A `%` followed by a digit
+that still doesn't parse (`%3x`) is an address error, never text for your own
+pane — while text that merely starts with `%` (`%s/foo/bar/`, `%!sort`) types
+as given, as does anything unmarked that is not a plain number (`3x`, `+5`). To
+type an address-shaped string, name the pane as well: `tty7 send %42 %3x`.
 
 `--key` presses a key instead of typing characters, which is what a pane wants
 once something is already running in it: answering a prompt that only takes