feat: scaffold BlackRoad OS Phase 2 infrastructure

Implements complete Phase 2 scaffold across 6 core modules:

## New Modules

### 1. Backend API Enhancements
- Add system router with /version, /config/public, /os/state endpoints
- Register system router in main.py
- Add comprehensive tests for system endpoints

### 2. Core OS Runtime (core_os/)
- Implement UserSession, Window, OSState models
- Add state management functions (open_window, close_window, etc.)
- Create Backend API adapter for communication
- Include full test suite for models and state

### 3. Operator Engine (operator_engine/)
- Build job registry with example jobs
- Implement simple scheduler with lifecycle management
- Optional HTTP server on port 8001
- Complete tests for jobs and scheduler

### 4. Web Client Enhancements
- Add CoreOSClient JavaScript class
- Integrate system API endpoints
- Event-driven architecture for state updates
- Zero dependencies, vanilla JavaScript

### 5. Prism Console (prism-console/)
- Modern dark-themed admin UI
- Multi-tab navigation (Overview, Jobs, Agents, Logs, System)
- Real-time metrics dashboard
- Backend API integration with auto-refresh

### 6. Documentation (codex-docs/)
- Complete MkDocs-based documentation
- Architecture guides and component docs
- Infrastructure setup guides
- API reference documentation

## CI/CD

- Add core-os-tests.yml workflow
- Add operator-tests.yml workflow
- Add docs-build.yml workflow

## Documentation

- Create BLACKROAD_OS_REPO_MAP.md cross-reference
- Add README for each module
- Comprehensive integration documentation

## Summary

- 37 new files created
- ~3,500 lines of new code
- 5 test suites with 15+ tests
- 3 new CI workflows
- 10+ documentation pages

All modules are minimal working skeletons ready for integration.
Designed to be extracted into separate repos if needed.

Phase 2 scaffold complete and ready for review.

core_os/state.py

@@ -0,0 +1,170 @@
+"""Core OS state management"""
+from typing import Optional, List
+import copy
+
+from core_os.models import OSState, Window, UserSession, WindowState
+
+
+# Global in-memory state (in production, this would be in Redis/DB)
+_current_state: Optional[OSState] = None
+
+
+def get_initial_state() -> OSState:
+    """
+    Get initial OS state
+
+    Returns:
+        Fresh OSState with default configuration
+    """
+    global _current_state
+
+    if _current_state is None:
+        _current_state = OSState(
+            session=UserSession(display_name="BlackRoad User"),
+            desktop_items=[
+                {
+                    "id": "my-computer",
+                    "label": "My Computer",
+                    "icon": "🖥️",
+                    "app_id": "computer",
+                },
+                {
+                    "id": "prism-console",
+                    "label": "Prism Console",
+                    "icon": "⚡",
+                    "app_id": "prism",
+                },
+                {
+                    "id": "lucidia",
+                    "label": "Lucidia",
+                    "icon": "🧠",
+                    "app_id": "lucidia",
+                },
+            ],
+            taskbar_items=[
+                {"id": "start-menu", "label": "Start", "icon": "🪟"},
+            ],
+            system_tray_items=[
+                {"id": "network", "icon": "🌐", "status": "connected"},
+                {"id": "volume", "icon": "🔊", "status": "on"},
+                {"id": "clock", "icon": "🕐", "status": "active"},
+            ],
+        )
+
+    return _current_state
+
+
+def get_current_state() -> OSState:
+    """Get current OS state (or initialize if not exists)"""
+    return get_initial_state()
+
+
+def open_window(app_id: str, title: Optional[str] = None) -> OSState:
+    """
+    Open a new window for the specified app
+
+    Args:
+        app_id: Application identifier
+        title: Window title (optional, defaults to app_id)
+
+    Returns:
+        Updated OS state
+    """
+    state = get_current_state()
+
+    # Create new window
+    window = Window(
+        app_id=app_id,
+        title=title or app_id.replace("-", " ").title(),
+        z_index=len(state.windows),
+    )
+
+    # Add to windows list
+    state.windows.append(window)
+    state.active_window_id = window.id
+
+    return state
+
+
+def close_window(window_id: str) -> OSState:
+    """
+    Close a window
+
+    Args:
+        window_id: Window identifier
+
+    Returns:
+        Updated OS state
+    """
+    state = get_current_state()
+
+    # Find and remove window
+    state.windows = [w for w in state.windows if w.id != window_id]
+
+    # Update active window if needed
+    if state.active_window_id == window_id:
+        state.active_window_id = state.windows[0].id if state.windows else None
+
+    return state
+
+
+def minimize_window(window_id: str) -> OSState:
+    """
+    Minimize a window
+
+    Args:
+        window_id: Window identifier
+
+    Returns:
+        Updated OS state
+    """
+    state = get_current_state()
+
+    for window in state.windows:
+        if window.id == window_id:
+            window.state = WindowState.MINIMIZED
+            break
+
+    return state
+
+
+def maximize_window(window_id: str) -> OSState:
+    """
+    Maximize a window
+
+    Args:
+        window_id: Window identifier
+
+    Returns:
+        Updated OS state
+    """
+    state = get_current_state()
+
+    for window in state.windows:
+        if window.id == window_id:
+            window.state = WindowState.MAXIMIZED
+            break
+
+    return state
+
+
+def set_active_window(window_id: str) -> OSState:
+    """
+    Set the active (focused) window
+
+    Args:
+        window_id: Window identifier
+
+    Returns:
+        Updated OS state
+    """
+    state = get_current_state()
+    state.active_window_id = window_id
+    return state
+
+
+def reset_state() -> OSState:
+    """Reset OS state to initial state"""
+    global _current_state
+    _current_state = None
+    return get_initial_state()