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.

backend/app/routers/system.py

@@ -0,0 +1,83 @@
+"""System endpoints for core OS operations"""
+from fastapi import APIRouter, Depends
+from sqlalchemy.ext.asyncio import AsyncSession
+from datetime import datetime
+import os
+
+from app.config import settings
+from app.database import get_db
+
+router = APIRouter(prefix="/api/system", tags=["system"])
+
+
+@router.get("/version")
+async def get_version():
+    """
+    Get system version and build information
+
+    Returns version, build time, environment, and git information
+    """
+    # Try to get git SHA if available
+    git_sha = os.environ.get("GIT_SHA", "development")
+
+    return {
+        "version": settings.APP_VERSION,
+        "build_time": datetime.utcnow().isoformat(),
+        "env": settings.ENVIRONMENT,
+        "git_sha": git_sha[:8] if len(git_sha) > 8 else git_sha,
+        "app_name": settings.APP_NAME,
+    }
+
+
+@router.get("/config/public")
+async def get_public_config():
+    """
+    Get public configuration (non-sensitive settings only)
+
+    Returns feature flags, environment info, and public settings
+    """
+    return {
+        "environment": settings.ENVIRONMENT,
+        "app_name": settings.APP_NAME,
+        "version": settings.APP_VERSION,
+        "features": {
+            "blockchain_enabled": True,
+            "ai_agents_enabled": True,
+            "video_streaming_enabled": True,
+            "gaming_enabled": True,
+            "social_enabled": True,
+        },
+        "limits": {
+            "max_upload_size_mb": 100,
+            "session_timeout_minutes": 60,
+        },
+        "external_services": {
+            "github_integration": bool(os.environ.get("GITHUB_TOKEN")),
+            "stripe_enabled": bool(os.environ.get("STRIPE_SECRET_KEY")),
+            "openai_enabled": bool(os.environ.get("OPENAI_API_KEY")),
+        },
+    }
+
+
+@router.get("/os/state")
+async def get_os_state(db: AsyncSession = Depends(get_db)):
+    """
+    Get current OS state (stub for now)
+
+    Returns the current state of the OS including:
+    - Active windows
+    - Running applications
+    - System resources
+    """
+    # TODO: Integrate with core_os module when implemented
+    return {
+        "status": "ok",
+        "uptime_seconds": 0,  # TODO: Track actual uptime
+        "active_windows": [],
+        "running_apps": [],
+        "system_resources": {
+            "memory_usage_percent": 0,
+            "cpu_usage_percent": 0,
+        },
+        "note": "This is a stub endpoint. Full OS state tracking coming in Phase 2.",
+    }