feat: implement dynamic pane resizing

- Add `resize_panes_equal()` to `Window`.
- Dynamically apply `tmux` layouts based on pane count.
- Implement `get_width()` and `get_height()` for `Pane`.
- Update test to create 4 panes and use equal resizing.

lib/osal/tmux/play.v

@@ -655,6 +655,9 @@ fn play_window_ensure(mut plbook PlayBook, mut tmux_instance Tmux) ! {
 					env:        env
 				)!
 			}
+
+			// After creating all panes, resize them to equal dimensions dynamically
+			window.resize_panes_equal()!
 		}
 
 		action.done = true

lib/osal/tmux/tmux_pane.v

@@ -201,3 +201,21 @@ pub fn (mut p Pane) resize_left(cells int) ! {
 pub fn (mut p Pane) resize_right(cells int) ! {
 	p.resize(direction: 'right', cells: cells)!
 }
+
+// Get current pane width
+pub fn (p Pane) get_width() !int {
+	cmd := 'tmux display-message -t ${p.window.session.name}:@${p.window.id}.%${p.id} -p "#{pane_width}"'
+	res := osal.exec(cmd: cmd, stdout: false, name: 'tmux_get_pane_width') or {
+		return error("Can't get pane width: ${err}")
+	}
+	return res.output.trim_space().int()
+}
+
+// Get current pane height
+pub fn (p Pane) get_height() !int {
+	cmd := 'tmux display-message -t ${p.window.session.name}:@${p.window.id}.%${p.id} -p "#{pane_height}"'
+	res := osal.exec(cmd: cmd, stdout: false, name: 'tmux_get_pane_height') or {
+		return error("Can't get pane height: ${err}")
+	}
+	return res.output.trim_space().int()
+}

lib/osal/tmux/tmux_window.v

@@ -274,6 +274,54 @@ pub fn (mut w Window) pane_split_vertical(cmd string) !&Pane {
 	return w.pane_split(cmd: cmd, horizontal: false)
 }
 
+// Resize panes to equal dimensions dynamically based on pane count
+pub fn (mut w Window) resize_panes_equal() ! {
+	w.scan()! // Refresh pane information
+
+	pane_count := w.panes.len
+	if pane_count <= 1 {
+		return
+	}
+
+	// Dynamic layout based on actual pane count
+	match pane_count {
+		1 {
+			// Single pane, no resizing needed
+			console.print_debug('Single pane, no resizing needed')
+		}
+		2 {
+			// Two panes: use even-horizontal layout (side by side)
+			cmd := 'tmux select-layout -t ${w.session.name}:@${w.id} even-horizontal'
+			osal.execute_silent(cmd) or {
+				console.print_debug('Could not apply even-horizontal layout: ${err}')
+			}
+		}
+		3 {
+			// Three panes: use main-horizontal layout (one large top, two smaller bottom)
+			cmd := 'tmux select-layout -t ${w.session.name}:@${w.id} main-horizontal'
+			osal.execute_silent(cmd) or {
+				console.print_debug('Could not apply main-horizontal layout: ${err}')
+			}
+		}
+		4 {
+			// Four panes: use tiled layout (2x2 grid)
+			cmd := 'tmux select-layout -t ${w.session.name}:@${w.id} tiled'
+			osal.execute_silent(cmd) or {
+				console.print_debug('Could not apply tiled layout: ${err}')
+			}
+		}
+		else {
+			// For 5+ panes: use tiled layout which works well for any number
+			if pane_count >= 5 {
+				cmd := 'tmux select-layout -t ${w.session.name}:@${w.id} tiled'
+				osal.execute_silent(cmd) or {
+					console.print_debug('Could not apply tiled layout for ${pane_count} panes: ${err}')
+				}
+			}
+		}
+	}
+}
+
 @[params]
 pub struct TtydArgs {
 pub mut: