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.

examples/osal/tmux/heroscripts/debug_test.heroscript

@@ -1,18 +0,0 @@
-#!/usr/bin/env hero
-
-// Debug test - no ttyd, just basic declarative functionality
-
-// Ensure a test session exists
-!!tmux.session_ensure
-    name:"debug_test"
-
-// Ensure a simple 2-pane window exists
-!!tmux.window_ensure
-    name:"debug_test|demo"
-    cat:"2pane"
-
-// Try to configure just one pane
-!!tmux.pane_ensure
-    name:"debug_test|demo|1"
-    label:"test"
-    cmd:"echo Hello from pane 1"

examples/osal/tmux/heroscripts/simple_declarative_test.heroscript

@@ -9,7 +9,7 @@
 // Ensure a simple 2-pane window exists
 !!tmux.window_ensure
     name:"test|demo"
-    cat:"2pane"
+    cat:"4pane"
 
 // Configure the panes
 !!tmux.pane_ensure
@@ -20,4 +20,14 @@
 !!tmux.pane_ensure
     name:"test|demo|2"
     label:"second"
-    cmd:"echo Second pane ready"
+    cmd:"echo Second pane ready"
+
+!!tmux.pane_ensure
+    name:"test|demo|3"
+    label:"third"
+    cmd:"echo Third pane ready"
+
+!!tmux.pane_ensure
+    name:"test|demo|4"
+    label:"fourth"
+    cmd:"echo Fourth pane ready"