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.

operator_engine/tests/test_jobs.py

@@ -0,0 +1,53 @@
+"""Tests for job management"""
+import pytest
+from operator_engine.jobs import Job, JobStatus, JobRegistry
+
+
+def test_job_creation():
+    """Test creating a job"""
+    job = Job(name="Test Job", schedule="*/5 * * * *")
+
+    assert job.name == "Test Job"
+    assert job.schedule == "*/5 * * * *"
+    assert job.status == JobStatus.PENDING
+    assert job.id is not None
+
+
+def test_job_to_dict():
+    """Test job serialization"""
+    job = Job(name="Test Job")
+    data = job.to_dict()
+
+    assert data["name"] == "Test Job"
+    assert data["status"] == "pending"
+    assert "id" in data
+    assert "created_at" in data
+
+
+def test_job_registry():
+    """Test job registry operations"""
+    registry = JobRegistry()
+
+    # Should have example jobs
+    jobs = registry.list_jobs()
+    assert len(jobs) > 0
+
+    # Add new job
+    new_job = Job(name="New Test Job")
+    added_job = registry.add_job(new_job)
+    assert added_job.id == new_job.id
+
+    # Get job
+    retrieved_job = registry.get_job(new_job.id)
+    assert retrieved_job is not None
+    assert retrieved_job.name == "New Test Job"
+
+    # Update job
+    updated_job = registry.update_job(new_job.id, status=JobStatus.RUNNING)
+    assert updated_job is not None
+    assert updated_job.status == JobStatus.RUNNING
+
+    # Remove job
+    removed = registry.remove_job(new_job.id)
+    assert removed is True
+    assert registry.get_job(new_job.id) is None