feat: Emacs-style reverse-video cursor (solid, no blink)

Replaced the software blinking █ cursor with a reverse-video cursor
that swaps foreground and background colors at the insertion point.
Solid at all times — no blink logic, no state tracking, no flicker.
- Removed duplicate cursor-visible-p functions
- Removed software cursor draw from view-input
- Removed terminal cursor style/show from initialize-backend
- position-cursor draws character at cursor with :bg fg + :input-fg bg

org/channel-tui-view.org

@@ -70,11 +70,6 @@ Returns a list of strings, one per line."
   ;; No clock, no dot, no text. Everything clean.
   )
 
-(defun cursor-visible-p ()
-  "Returns T if the blinking cursor should be visible this frame (2Hz)."
-  (evenp (floor (get-internal-real-time)
-                (floor internal-time-units-per-second 2))))
-
 (defun input-panel-top (chat-w h)
   "Compute the top row of the input panel based on current input buffer."
   (let* ((hpad 2)
@@ -248,13 +243,9 @@ Returns a list of strings, one per line."
             (setf cursor-line i
                   cursor-col (- pos accum)))
           (incf accum (1+ len))))
-      ;; Draw software blinking cursor at insertion point
-      (when (cursor-visible-p)
-        (let ((cursor-row (+ panel-top 1 cursor-line)))
-          (cl-tty.backend:draw-text fb (+ hpad 2 cursor-col) cursor-row "█" input-fg nil))))
     ;; Hint — lowercase, right-aligned at h-2
     (let ((hint "ctrl+p | /help"))
-      (cl-tty.backend:draw-text fb (- chat-w (length hint) 2) (- h 2) hint hint-fg (theme-color :bg)))))
+      (cl-tty.backend:draw-text fb (- chat-w (length hint) 2) (- h 2) hint hint-fg (theme-color :bg))))))
 #+end_src
 
 ** Sidebar
@@ -328,13 +319,9 @@ Returns a list of strings, one per line."
     (position-cursor fb w h)
     (setf (st :dirty) (list nil nil nil))))
 
-(defun cursor-visible-p ()
-  "Returns T if the software-cursor should be visible this frame (2Hz)."
-  (evenp (floor (get-internal-real-time)
-                (floor internal-time-units-per-second 2))))
-
 (defun position-cursor (fb w h)
-  "Position terminal cursor at input insertion point and draw █ software cursor."
+  "Reverse-video cursor (Emacs style): shows the character at cursor position
+with foreground and background colors swapped."
   (let* ((sw (if (sidebar-visible-p w) (or (st :sidebar-width) 42) 0))
          (cw (- w sw))
          (hpad 2)
@@ -343,11 +330,11 @@ Returns a list of strings, one per line."
          (prompt-w (- cw (* 2 hpad) 2))
          (display-start (max 0 (- pos (1- prompt-w))))
          (cx (+ hpad 2 (- pos display-start)))
-         (cy (- h 6)))
-    (cl-tty.backend:cursor-move fb cx cy)
-    (cl-tty.backend:cursor-style fb :block :blink t)
-    ;; Software █ cursor — erase old position with space, draw new position
-    (cl-tty.backend:draw-text fb cx cy (if (cursor-visible-p) "█" " ") (theme-color :input-fg) nil)))
+         (cy (- h 6))
+         (ch (if (< pos (length text)) (char text pos) #\Space)))
+    (cl-tty.backend:draw-text fb cx cy (string ch)
+                               (theme-color :bg)         ;; fg = global bg (black)
+                               (theme-color :input-fg)))) ;; bg = text color (reverse)
 #+END_SRC
 
 * Implementation — v0.7.0 additions