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/models.py

@@ -0,0 +1,129 @@
+"""Core OS data models"""
+from dataclasses import dataclass, field
+from datetime import datetime
+from typing import List, Optional, Dict, Any
+from enum import Enum
+import uuid
+
+
+class WindowState(str, Enum):
+    """Window state"""
+
+    NORMAL = "normal"
+    MINIMIZED = "minimized"
+    MAXIMIZED = "maximized"
+    CLOSED = "closed"
+
+
+@dataclass
+class UserSession:
+    """
+    Represents a user session in BlackRoad OS
+
+    Attributes:
+        id: Unique session identifier
+        user_id: User ID (from auth system)
+        display_name: Display name for the session
+        created_at: Session creation timestamp
+        last_activity: Last activity timestamp
+        metadata: Additional session metadata
+    """
+
+    id: str = field(default_factory=lambda: str(uuid.uuid4()))
+    user_id: Optional[str] = None
+    display_name: str = "Guest"
+    created_at: datetime = field(default_factory=datetime.utcnow)
+    last_activity: datetime = field(default_factory=datetime.utcnow)
+    metadata: Dict[str, Any] = field(default_factory=dict)
+
+    def to_dict(self) -> Dict[str, Any]:
+        """Convert to dictionary"""
+        return {
+            "id": self.id,
+            "user_id": self.user_id,
+            "display_name": self.display_name,
+            "created_at": self.created_at.isoformat(),
+            "last_activity": self.last_activity.isoformat(),
+            "metadata": self.metadata,
+        }
+
+
+@dataclass
+class Window:
+    """
+    Represents a window in the OS
+
+    Attributes:
+        id: Unique window identifier
+        app_id: Application identifier
+        title: Window title
+        state: Window state (normal, minimized, maximized)
+        position: Window position (x, y)
+        size: Window size (width, height)
+        z_index: Z-index for layering
+        created_at: Window creation timestamp
+        metadata: Additional window metadata
+    """
+
+    id: str = field(default_factory=lambda: str(uuid.uuid4()))
+    app_id: str = ""
+    title: str = "Untitled"
+    state: WindowState = WindowState.NORMAL
+    position: tuple[int, int] = (100, 100)
+    size: tuple[int, int] = (800, 600)
+    z_index: int = 0
+    created_at: datetime = field(default_factory=datetime.utcnow)
+    metadata: Dict[str, Any] = field(default_factory=dict)
+
+    def to_dict(self) -> Dict[str, Any]:
+        """Convert to dictionary"""
+        return {
+            "id": self.id,
+            "app_id": self.app_id,
+            "title": self.title,
+            "state": self.state.value,
+            "position": {"x": self.position[0], "y": self.position[1]},
+            "size": {"width": self.size[0], "height": self.size[1]},
+            "z_index": self.z_index,
+            "created_at": self.created_at.isoformat(),
+            "metadata": self.metadata,
+        }
+
+
+@dataclass
+class OSState:
+    """
+    Represents the current state of the operating system
+
+    Attributes:
+        session: Current user session
+        windows: List of open windows
+        active_window_id: ID of the currently active window
+        desktop_items: Desktop icons/shortcuts
+        taskbar_items: Taskbar items
+        system_tray_items: System tray items
+        theme: Current theme name
+        metadata: Additional OS state metadata
+    """
+
+    session: UserSession = field(default_factory=UserSession)
+    windows: List[Window] = field(default_factory=list)
+    active_window_id: Optional[str] = None
+    desktop_items: List[Dict[str, Any]] = field(default_factory=list)
+    taskbar_items: List[Dict[str, Any]] = field(default_factory=list)
+    system_tray_items: List[Dict[str, Any]] = field(default_factory=list)
+    theme: str = "classic"
+    metadata: Dict[str, Any] = field(default_factory=dict)
+
+    def to_dict(self) -> Dict[str, Any]:
+        """Convert to dictionary"""
+        return {
+            "session": self.session.to_dict(),
+            "windows": [w.to_dict() for w in self.windows],
+            "active_window_id": self.active_window_id,
+            "desktop_items": self.desktop_items,
+            "taskbar_items": self.taskbar_items,
+            "system_tray_items": self.system_tray_items,
+            "theme": self.theme,
+            "metadata": self.metadata,
+        }