fix(ui): reserve pad height per message to prevent multi-line clip and scroll desync

A tall multi-line message printed near the bottom of the ncurses pad was clipped because _win_print_internal grew the pad from the current cursor only (_win_ensure_pad_capacity(getcury)), not the height of the message about to be printed. The clipped message's captured height (e.g. 1 row for a 49-row message) was wrong while win_redraw later rendered it in full; the resulting buffer->lines / y_start_pos mismatch desynced the page-up scroll anchor, producing a ~one-page jump when scrolling past such messages from history.

Estimate the rendered height (hard newlines + soft-wrap over the usable width) and reserve that many rows before printing, so the message is never clipped and its captured height matches the redraw. All print paths go through _win_print_internal, so incoming/outgoing/history are covered.

Regression from the upstream sync (72f4f186d), which replaced the fixed-size pad with the dynamic _win_ensure_pad_capacity model.

src/ui/window.c

@@ -67,6 +67,23 @@ _win_ensure_pad_capacity(ProfWin* window, WINDOW* win, int lines_needed)
         }
     }
 }
+
+// upper-bound estimate of rows a message body occupies (hard newlines + soft-wrap), to reserve pad space before printing so a tall message isn't clipped (a clipped height desyncs the scroll offset)
+static int
+_win_estimated_lines(WINDOW* win, const char* const message, int indent, int pad_indent)
+{
+    int usable = getmaxx(win) - (indent + pad_indent);
+    if (usable < 1) {
+        usable = 1;
+    }
+    int newlines = 0;
+    for (const char* p = message; *p; p++) {
+        if (*p == '\n') {
+            newlines++;
+        }
+    }
+    return newlines + utf8_display_len(message) / usable + 2;
+}
 static const char* LOADING_MESSAGE = "Loading older messages…";
 static const char* CONS_WIN_TITLE = "CProof. Type /help for help information.";
 static const char* XML_WIN_TITLE = "XML Console";
@@ -2001,19 +2018,7 @@ _win_print_internal(ProfWin* window, const char* show_char, int pad_indent, GDat
         }
     }
 
-    // reserve pad rows for this message's full height so a tall message isn't clipped at the pad bottom (a clipped height desyncs the scroll offset)
-    int usable = getmaxx(window->layout->win) - (indent + pad_indent);
-    if (usable < 1) {
-        usable = 1;
-    }
-    int msg_nl = 0;
-    for (const char* mp = message + offset; *mp; mp++) {
-        if (*mp == '\n') {
-            msg_nl++;
-        }
-    }
-    int est_lines = msg_nl + (int)(utf8_display_len(message + offset) / usable) + 2;
-    _win_ensure_pad_capacity(window, window->layout->win, getcury(window->layout->win) + est_lines);
+    _win_ensure_pad_capacity(window, window->layout->win, getcury(window->layout->win) + _win_estimated_lines(window->layout->win, message + offset, indent, pad_indent));
 
     if (prefs_get_boolean(PREF_WRAP)) {
         _win_print_wrapped(window->layout->win, message + offset, indent, pad_indent);