fix(gui): Resolve Text Viewer docking conflict with unified ID

- Update Text Viewer window ID to '###Text_Viewer_Unified'.
- Ensures ImGui treats the window as a single stable entity across title changes.
- Prevents docking loop glitches.

conductor/tracks/phase7_monolithic_stabilization_20260602/spec.md

@@ -1,7 +1,7 @@
 # Specification: Phase 7 Monolithic Stabilization
 
 ## 1. Current State Audit
-*   **Window Management:** `render_text_viewer_window` (gui_2.py:3843) uses ID `###Text_Viewer_Stable`. Call site at line 1226 is direct. Registry key is `"Text Viewer"`.
+*   **Window Management:** `render_text_viewer_window` (gui_2.py:3843) uses ID `###Text_Viewer_Unified`. Call site at line 1226 is direct. Registry key is `"Text Viewer"`.
 *   **Rendering Logic:** Discussion entries are currently delegated to `src/discussion_entry_renderer.py`, which is causing `ImportError` and `access violation` crashes in unit tests due to mock patching limits.
 *   **Markdown Tables:** Content is vertically squashed because the `begin_group` width is determined by small header buttons, not the full panel.
 *   **MiniMax Support:** `run_discussion_compression` exists but may have routing nuances or base URL mismatches with the M3 model.

src/gui_2.py

@@ -4004,7 +4004,7 @@ def render_text_viewer_window(app: App) -> None:
  """Renders the standalone text/code/markdown viewer window."""
  if not app.show_windows.get("Text Viewer", False): return
  imgui.set_next_window_size(imgui.ImVec2(900, 700), imgui.Cond_.first_use_ever)
- expanded, opened = imgui.begin(f"{app.text_viewer_title or 'Text Viewer'}###Text_Viewer_Stable", True, imgui.WindowFlags_.no_collapse)
+ expanded, opened = imgui.begin(f"{app.text_viewer_title or 'Text Viewer'}###Text_Viewer_Unified", True, imgui.WindowFlags_.no_collapse)
  app.show_windows["Text Viewer"] = bool(opened)
  if not opened:
   app.ui_editing_slices_file = None

tests/test_gui_text_viewer_docking.py

@@ -25,7 +25,7 @@ def test_text_viewer_window_id_stability():
   # Verify imgui.begin was called with the stable ID suffix
   args, _ = mock_imgui.begin.call_args
   window_title = args[0]
-  assert "###Text_Viewer_Stable" in window_title
+  assert "###Text_Viewer_Unified" in window_title
   assert window_title.startswith("Custom Title")
 
 def test_text_viewer_window_default_title_id_stability():
@@ -50,5 +50,5 @@ def test_text_viewer_window_default_title_id_stability():
   # Verify imgui.begin was called with the stable ID suffix
   args, _ = mock_imgui.begin.call_args
   window_title = args[0]
-  assert "###Text_Viewer_Stable" in window_title
+  assert "###Text_Viewer_Unified" in window_title
   assert window_title.startswith("Text Viewer")