fix: add missing keyword clause in printable branch of on-key

The revert removed the (keyword ...) clause from the typecase in
on-key's printable branch. Keyword symbols from the main loop
(:a, :h, etc.) fell through to (t nil), making all character input
silently ignored. Typing and sending now works correctly.

lisp/channel-tui-main.lisp

@@ -566,7 +566,9 @@
        (t
          (let ((chr (typecase ch
                       (character ch)
-                     (integer (code-char ch))
+                      ((integer 32 126) (code-char ch))
+                      (keyword (let ((s (string ch)))
+                                 (and (= (length s) 1) (char-downcase (char s 0)))))
                       (t nil))))
           (when (and chr (graphic-char-p chr))
             (input-insert-char chr)

org/channel-tui-main.org

@@ -600,7 +600,9 @@ Event handlers + daemon I/O + main loop.
        (t
          (let ((chr (typecase ch
                       (character ch)
-                     (integer (code-char ch))
+                      ((integer 32 126) (code-char ch))
+                      (keyword (let ((s (string ch)))
+                                 (and (= (length s) 1) (char-downcase (char s 0)))))
                       (t nil))))
           (when (and chr (graphic-char-p chr))
             (input-insert-char chr)