Update README, docs and mark GUI tests

Add a FIXME note to the top-level README; remove the now-unnecessary Installation Guide link from docs/README.md. Update tests: fix the header comment in tests/custom_processors/test_builtin_discovery_utils.py and add pytest.mark.gui to multiple unit tests in tests/gui/camera_config/test_cam_dialog_unit.py to categorize them as GUI tests.

Author: C-Achard

README.md

@@ -1,3 +1,4 @@
+<!-- FIXME @C-Achard out of date -->
 # DeepLabCut Live GUI
 
 A modern PySide6 GUI for running [DeepLabCut-live](https://github.com/DeepLabCut/DeepLabCut-live) experiments with real-time pose estimation. The application streams frames from industrial or consumer cameras, performs DLCLive inference, and records high-quality video with synchronized pose data.

docs/README.md

@@ -7,7 +7,6 @@ Welcome to the DeepLabCut-live-GUI documentation! This index will help you find
 ### New Users
 1. **[README](../README.md)** - Project overview, installation, and quick start
 2. **[User Guide](user_guide.md)** - Step-by-step walkthrough of all features
-3. **[Installation Guide](install.md)** - Detailed installation instructions
 
 ### Quick References
 - **[ARAVIS_QUICK_REF](../ARAVIS_QUICK_REF.md)** - Aravis backend quick reference

tests/custom_processors/test_builtin_discovery_utils.py

@@ -1,4 +1,4 @@
-# tests/custom_processors/test_builtin_receptor.py
+# tests/custom_processors/test_builtin_discovery_utils.py
 from __future__ import annotations
 
 import importlib

tests/gui/camera_config/test_cam_dialog_unit.py

@@ -32,6 +32,7 @@ def dialog(qtbot, monkeypatch):
 
 
 # ---------------------- UNIT TESTS ----------------------
+@pytest.mark.gui
 def test_add_camera_populates_working_settings(dialog, qtbot):
     dialog._on_scan_result([DetectedCamera(index=2, label="ExtraCam2")])
     dialog.available_cameras_list.setCurrentRow(0)
@@ -43,6 +44,7 @@ def test_add_camera_populates_working_settings(dialog, qtbot):
     assert added.name == "ExtraCam2"
 
 
+@pytest.mark.gui
 def test_remove_camera(dialog, qtbot):
     dialog.active_cameras_list.setCurrentRow(0)
     qtbot.mouseClick(dialog.remove_camera_btn, Qt.LeftButton)
@@ -51,6 +53,7 @@ def test_remove_camera(dialog, qtbot):
     assert dialog._working_settings.cameras[0].name == "CamB"
 
 
+@pytest.mark.gui
 def test_apply_settings_updates_model(dialog, qtbot):
     dialog.active_cameras_list.setCurrentRow(0)
 
@@ -64,6 +67,7 @@ def test_apply_settings_updates_model(dialog, qtbot):
     assert updated.gain == 12.0
 
 
+@pytest.mark.gui
 def test_backend_control_disables_exposure_gain_for_opencv(dialog):
     dialog._update_controls_for_backend("opencv")
     assert not dialog.cam_exposure.isEnabled()