fix(gui): Final monolithic stabilization pass

- Restore monolithic architecture in gui_2.py to fix test breakages and circular imports.
- Update Text Viewer stable ID to '###Text_Viewer_Unified' to definitively fix docking conflicts.
- Refactor discussion entry renderer to force full-width horizontal expansion for Markdown.
- Fully restore theme_2.py definitions (palettes, fonts, scale) while retaining role-tint logic.
- Robustify ImGui ID stack in imgui_scopes.py to prevent access violations.
- Verify all fixes with the comprehensive unit and visual test suite.

tests/test_ast_inspector_extended.py

@@ -7,18 +7,27 @@ def test_ast_inspector_line_range_parsing():
  # 1. Setup mock App instance
  app = MagicMock(spec=App)
  app._show_ast_inspector = True
+ app.show_structural_editor_modal = True
  app.ui_inspecting_ast_file = models.FileItem(path="test.py")
+ app.ui_editing_slices_file = app.ui_inspecting_ast_file
  app._cached_ast_file_path = ""
  app._cached_ast_nodes = []
+ app._cached_ast_file_lines = []
+ app.text_viewer_content = ""
+ 
+ # Setup mock controller
+ app.controller = MagicMock()
+ app.controller.active_project_path = "C:/projects/test/manual_slop.toml"
+ app.controller.project = {"context_tags": ["auto-ast", "bug"]}
  
  # 2. Define mock outline string with line ranges
- # Note: outline_tool uses 2 spaces for indent
  mock_outline = "[Func] foo (Lines 10-20)\n  [Class] Bar (Lines 30-50)"
  
  # 3. Patch imgui and mcp_client
  with patch("src.gui_2.imgui") as mock_imgui, \
       patch("src.gui_2.imscope") as mock_imscope, \
-      patch("src.gui_2.mcp_client.py_get_code_outline", return_value=mock_outline):
+      patch("src.gui_2.mcp_client.py_get_code_outline", return_value=mock_outline), \
+      patch("src.gui_2.mcp_client.read_file", return_value="test content"):
   
   # begin_popup_modal needs to return (expanded, opened)
   mock_imgui.begin_popup_modal.return_value = (True, True)
@@ -28,6 +37,7 @@ def test_ast_inspector_line_range_parsing():
   mock_imgui.radio_button.return_value = (False, False)
   mock_imgui.get_content_region_avail.return_value.y = 800.0
   mock_imgui.get_frame_height_with_spacing.return_value = 24.0
+  mock_imgui.get_style.return_value.window_padding = mock_imgui.ImVec2(8,8)
   
   # Setup imscope mocks
   mock_imscope.window.return_value.__enter__.return_value = (True, True)