fix(project): Create persona_manager in _load_active_project + handle missing context preset

Two fixes for the regression introduced in b92daef3 (and an additional
hardening for the persona->context_preset stale-reference class of bug):

1. Regression: persona_manager was missing on first project load.
   _load_active_project creates preset_manager and tool_preset_manager
   but did not create persona_manager, so the new
   self.personas = self.persona_manager.load_all() line in
   _refresh_from_project raised AttributeError on app startup before
   the post-_load_active_project persona_manager creation could run.
   Fix: create self.persona_manager in _load_active_project alongside
   the other managers, so the manager is available when
   _refresh_from_project runs.

2. Stale reference: persona's context_preset field pointed to a
   preset (e.g. 'GTE') that no longer exists in the project, causing
   load_context_preset to raise KeyError and crash the persona
   selector panel (which triggered the cascading 'Missing End()' imgui
   assertion).
   Fix: wrap the load_context_preset call in render_persona_selector_panel
   with try/except KeyError, surface the error in app.ai_status, and
   clear app.ui_active_context_preset to keep the GUI state consistent.

Tests: 2 new tests in tests/test_project_switch_persona_preset.py
- test_load_active_project_creates_persona_manager (regression guard)
- test_load_context_preset_missing_raises_keyerror (verifies the
  contract that load_context_preset raises for missing names; the
  GUI layer is now responsible for catching the error)

src/app_controller.py

@@ -2009,6 +2009,8 @@ class AppController:
     self.project_paths.append(fallback_path)
   self.preset_manager = presets.PresetManager(Path(self.active_project_path).parent if self.active_project_path else None)
   self.tool_preset_manager = tool_presets.ToolPresetManager(Path(self.active_project_path).parent if self.active_project_path else None)
+  from src.personas import PersonaManager
+  self.persona_manager = PersonaManager(Path(self.active_project_path).parent if self.active_project_path else None)
   self._refresh_from_project()
   self._configure_mcp_for_project()
 

src/gui_2.py

@@ -2140,7 +2140,11 @@ def render_persona_selector_panel(app: App) -> None:
       ai_client.set_bias_profile(persona.bias_profile)
      if getattr(persona, 'context_preset', None):
       app.ui_active_context_preset = persona.context_preset
-      app.load_context_preset(persona.context_preset)
+      try:
+       app.load_context_preset(persona.context_preset)
+      except KeyError as e:
+       app.ai_status = f"persona context preset missing: {e}"
+       app.ui_active_context_preset = ""
   imgui.end_combo()
  imgui.same_line()
  if imgui.button("Manage Personas"):