refactor: remove split_pane_manager plugin and harden view handling

- Delete deprecated split_pane_manager command plugin and all related commands
- Introduce new split_pane command structure (untracked replacement)
- Add guard in code_minimap to handle missing active view
- Prevent language detection for non-file buffers in command_helpers

This cleans up legacy split pane logic and improves stability for edge cases.

plugins/code/commands/split_pane/create_split_view.py

@@ -0,0 +1,77 @@
+# Python imports
+
+# Lib imports
+import gi
+
+gi.require_version("Gtk", "3.0")
+
+from gi.repository import Gtk
+
+# Application imports
+from libs.event_factory import Event_Factory, Code_Event_Types
+from libs.dto.states import SourceViewStates
+
+
+
+emit_to: callable = None
+
+def execute(
+    source_view1,
+    char_str,
+    modkeys_states
+):
+    logger.debug("Command: Split Pane")
+
+    scrolled_win1  = source_view1.get_parent()
+    container      = scrolled_win1.get_parent()
+    pane           = Gtk.Paned()
+    event          = Event_Factory.create_event(
+        "create_source_view",
+        state = SourceViewStates.INSERT
+    )
+    emit_to("source_views", event)
+
+    scrolled_win2,    \
+    source_view2      = event.response
+    old_sibling_right = None
+
+    if source_view1.sibling_right:
+        old_sibling_right = source_view1.sibling_right
+
+    source_view1.sibling_right = source_view2
+    if old_sibling_right:
+        old_sibling_right.sibling_left = source_view2
+        source_view2.sibling_right     = old_sibling_right
+
+    source_view2.sibling_left  = source_view1
+
+    pane.set_hexpand(True)
+    pane.set_vexpand(True)
+    pane.set_wide_handle(True)
+
+    container.remove(scrolled_win1)
+    pane.pack1( scrolled_win1, True, True )
+    pane.pack2( scrolled_win2, True, True )
+    container.add(pane)
+
+    def _show(pane, alloc, is_vertical: bool):
+        if is_vertical:
+            pane.set_position(alloc.width  / 2)
+        else:
+            pane.set_position(alloc.height / 2)
+
+        pane.disconnect(pane.show_id)
+
+    is_control, is_shift, is_alt = modkeys_states
+    alloc = container.get_allocation()
+    if char_str == "|":
+        pane.show_id = pane.connect("show", _show, alloc, True)
+        pane.set_orientation(Gtk.Orientation.VERTICAL)
+    elif char_str == "\\":
+        pane.show_id = pane.connect("show", _show, alloc, False)
+        pane.set_orientation(Gtk.Orientation.HORIZONTAL)
+
+    pane.show_all()
+
+    source_view2.command.exec("new_file")
+    source_view2.grab_focus()