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/tests/test_state.py

@@ -0,0 +1,95 @@
+"""Tests for OS state management"""
+import pytest
+from core_os.state import (
+    get_initial_state,
+    get_current_state,
+    open_window,
+    close_window,
+    minimize_window,
+    maximize_window,
+    set_active_window,
+    reset_state,
+)
+from core_os.models import WindowState
+
+
+def test_get_initial_state():
+    """Test getting initial OS state"""
+    reset_state()  # Reset to clean state
+    state = get_initial_state()
+
+    assert state is not None
+    assert state.session is not None
+    assert len(state.desktop_items) > 0
+    assert len(state.taskbar_items) > 0
+
+
+def test_open_window():
+    """Test opening a new window"""
+    reset_state()
+    initial_count = len(get_current_state().windows)
+
+    state = open_window("notepad", "Notepad")
+
+    assert len(state.windows) == initial_count + 1
+    assert state.windows[-1].app_id == "notepad"
+    assert state.windows[-1].title == "Notepad"
+    assert state.active_window_id == state.windows[-1].id
+
+
+def test_close_window():
+    """Test closing a window"""
+    reset_state()
+
+    # Open a window first
+    state = open_window("test-app")
+    window_id = state.windows[0].id
+    initial_count = len(state.windows)
+
+    # Close it
+    state = close_window(window_id)
+
+    assert len(state.windows) == initial_count - 1
+
+
+def test_minimize_window():
+    """Test minimizing a window"""
+    reset_state()
+
+    # Open and minimize
+    state = open_window("test-app")
+    window_id = state.windows[0].id
+
+    state = minimize_window(window_id)
+
+    assert state.windows[0].state == WindowState.MINIMIZED
+
+
+def test_maximize_window():
+    """Test maximizing a window"""
+    reset_state()
+
+    # Open and maximize
+    state = open_window("test-app")
+    window_id = state.windows[0].id
+
+    state = maximize_window(window_id)
+
+    assert state.windows[0].state == WindowState.MAXIMIZED
+
+
+def test_set_active_window():
+    """Test setting active window"""
+    reset_state()
+
+    # Open two windows
+    open_window("app1")
+    open_window("app2")
+
+    state = get_current_state()
+    first_window_id = state.windows[0].id
+
+    # Set first window as active
+    state = set_active_window(first_window_id)
+
+    assert state.active_window_id == first_window_id