docs(devcontainer): add comprehensive volume, health check, and GPU documentation

MEDIUM PRIORITY openai#6, openai#7, openai#8: COMPLETED

Volume Documentation:
- Added cleanup column to volume table
- Documented each volume's purpose and safety
- Added volume management commands (view sizes, clean caches)
-  Marked dangerous operations (database volumes)
- Provided docker-compose down -v cleanup instructions

Health Check Documentation:
- Added comprehensive health check table (interval, timeout, retries, start period)
- Documented health check commands (ps, inspect, logs)
- Provided tuning guidance for slower systems
- Explained why app-dev has no health check (uses sleep infinity)

GPU Support Documentation:
- Comprehensive requirements section (hardware, drivers, Docker Desktop)
- Configuration examples from docker-compose.yml
- Verification commands (nvidia-smi, torch.cuda)
- Troubleshooting guide:
  * WSL2 GPU support setup
  * Docker Desktop settings
  * Graceful CPU fallback
  * How to disable GPU reservation
- Usage notes (optional, graceful degradation, performance benefits)

All MEDIUM priority documentation items now complete!

Author: DeanLuus22021994

.devcontainer/README.md

@@ -77,15 +77,68 @@ Press `Ctrl+Shift+P` → `Tasks: Run Task` to use these.
 
 ### Volumes
 
-| Volume | Purpose | Mount Point |
-|--------|---------|-------------|
-| `vscode-extensions` | VS Code extensions persistence | `/home/vscode/.vscode-server` |
-| `python-cache` | Python package cache | `/opt/python-cache` |
-| `pytest-cache` | Pytest cache | `/opt/pytest-cache` |
-| `mypy-cache` | Type checking cache | `/opt/mypy-cache` |
-| `ruff-cache` | Ruff linter cache | `/opt/ruff-cache` |
-| `postgres-data` | PostgreSQL data persistence | `/var/lib/postgresql/data` |
-| `redis-data` | Redis data persistence | `/data` |
+| Volume | Purpose | Mount Point | Cleanup |
+|--------|---------|-------------|---------|
+| `vscode-extensions` | VS Code extensions persistence | `/home/vscode/.vscode-server` | Safe to delete if corrupted |
+| `python-cache` | Python package cache (pip/uv) | `/opt/python-cache` | Improves dependency install speed |
+| `pytest-cache` | Pytest test result cache | `/opt/pytest-cache` | Speeds up test execution |
+| `mypy-cache` | Type checking cache | `/opt/mypy-cache` | Reduces mypy analysis time |
+| `ruff-cache` | Ruff linter/formatter cache | `/opt/ruff-cache` | Speeds up linting/formatting |
+| `postgres-data` | PostgreSQL database persistence | `/var/lib/postgresql/data` | ⚠️ Contains all database data |
+| `redis-data` | Redis persistence (RDB/AOF) | `/data` | ⚠️ Contains state/pub-sub data |
+
+**Volume Management**:
+
+```bash
+# View volume sizes
+docker system df -v
+
+# Clean development caches (safe - will rebuild)
+docker volume rm openai-agents-python_python-cache
+docker volume rm openai-agents-python_pytest-cache
+docker volume rm openai-agents-python_mypy-cache
+docker volume rm openai-agents-python_ruff-cache
+
+# ⚠️ DANGER: Remove database volumes (deletes all data!)
+docker volume rm openai-agents-python_postgres-data
+docker volume rm openai-agents-python_redis-data
+
+# Clean all volumes (requires recreating containers)
+docker-compose down -v
+```
+
+### Health Checks
+
+Services are configured with health checks optimized for development:
+
+| Service | Interval | Timeout | Retries | Start Period | Notes |
+|---------|----------|---------|---------|--------------|-------|
+| **redis** | 5s | 3s | 5 | 10s | Fast startup, reliable |
+| **postgres** | 5s | 3s | 5 | 10s | Database initialization time |
+| **app-dev** | None | - | - | - | Uses `sleep infinity` in dev |
+
+**Health Check Commands**:
+
+```bash
+# Check all service health
+docker-compose ps
+
+# View specific service health
+docker inspect openai-agents-redis --format='{{.State.Health.Status}}'
+
+# View health check logs
+docker inspect openai-agents-postgres --format='{{range .State.Health.Log}}{{.Output}}{{end}}'
+```
+
+**Tuning for Development**:
+The default 5s intervals are suitable for development. For slower systems, increase in `docker-compose.yml`:
+
+```yaml
+healthcheck:
+  interval: 10s  # Reduce overhead on slower systems
+  timeout: 5s
+  retries: 3
+```
 
 ## Docker Debug Integration
 
@@ -427,6 +480,139 @@ if ($env:TERM_PROGRAM -eq "vscode") { . "$(code --locate-shell-integration-path
 
 Check if shell integration is active:
 
+```powershell
+# Check environment variable (PowerShell 7+ only)
+if ($env:VSCODE_SHELL_INTEGRATION) {
+    Write-Host "Shell integration is active!" -ForegroundColor Green
+}
+```
+
+## GPU Support
+
+NVIDIA GPU support is **optionally configured** for both development and production containers.
+
+### Requirements
+
+- **Hardware**: NVIDIA GPU (GTX/RTX series or Tesla)
+- **Windows**: NVIDIA drivers + WSL2 with GPU support
+- **Linux**: NVIDIA drivers + NVIDIA Container Toolkit
+- **Docker Desktop**: Latest version with GPU support enabled
+
+### Configuration
+
+GPU reservation is defined in `docker-compose.yml`:
+
+```yaml
+deploy:
+  resources:
+    reservations:
+      devices:
+        - driver: nvidia
+          capabilities: [gpu]
+          count: all  # Use all available GPUs
+```
+
+### Verification
+
+**Check GPU availability**:
+
+```bash
+# From host (Windows with NVIDIA GPU)
+nvidia-smi
+
+# Inside DevContainer
+docker-compose exec app-dev nvidia-smi
+
+# Or use Python
+docker-compose exec app-dev python -c "import torch; print(f'CUDA available: {torch.cuda.is_available()}, Devices: {torch.cuda.device_count()}')"
+```
+
+### Troubleshooting
+
+**GPU not detected?**
+
+1. **Windows WSL2**: Ensure NVIDIA drivers are updated and WSL2 has GPU support
+   ```powershell
+   wsl --update
+   nvidia-smi  # Should work in WSL2
+   ```
+
+2. **Docker Desktop**: Enable GPU support in Settings → Resources → WSL Integration
+
+3. **No GPU available**: Application will gracefully fall back to CPU
+   - OpenAI Agents SDK works fine without GPU
+   - GPU primarily benefits local model inference (if used)
+
+4. **Disable GPU reservation**: Comment out the `deploy.resources.reservations` section in `docker-compose.yml`:
+   ```yaml
+   # deploy:
+   #   resources:
+   #     reservations:
+   #       devices:
+   #         - driver: nvidia
+   #           capabilities: [gpu]
+   #           count: all
+   ```
+
+### GPU Usage Notes
+
+- **Optional**: GPU support is not required for the OpenAI Agents SDK
+- **Graceful Degradation**: Application automatically uses CPU if GPU unavailable
+- **Performance**: Benefits local model inference and training (if implemented)
+- **Resource Limits**: Production container has memory/CPU limits; adjust as needed
+
+---
+
+## Terminal Shell Integration
+
+VS Code terminal shell integration provides enhanced terminal features including command navigation, decorations, IntelliSense, and debugging capabilities.
+
+### Features
+
+- **Command Navigation**: Navigate commands with Ctrl/Cmd+Up/Down
+- **Command Decorations**: Visual success/failure indicators with exit codes
+- **Quick Fixes**: Automatic suggestions for common errors (git, ports, etc.)
+- **IntelliSense**: Context-aware completions for files, commands, and arguments
+- **Run Recent Command**: Quick access to history (Ctrl+Alt+R)
+- **Go to Recent Directory**: Quick cd navigation (Ctrl+G)
+- **Sticky Scroll**: Shows current command at viewport top
+- **Enhanced Accessibility**: Command navigation in accessible buffer, audio cues
+
+### Configuration Status
+
+Shell integration is **enabled** via `.vscode/settings.json`:
+
+```json
+{
+  "terminal.integrated.shellIntegration.enabled": true,
+  "terminal.integrated.enablePersistentSessions": true
+}
+```
+
+### Supported Shells
+
+- **PowerShell 7+** (pwsh): Full support with Rich quality
+- **Windows PowerShell 5.1**: Not supported (automatic injection disabled)
+- **Bash/Zsh** (Linux): Full support with Rich quality
+
+### Setup for PowerShell 7+
+
+If using PowerShell 7+ (recommended), run the automated setup:
+
+```powershell
+.\scripts\setup-shell-integration.ps1
+```
+
+Or manually add to your PowerShell profile (`code $Profile`):
+
+```powershell
+if ($env:TERM_PROGRAM -eq "vscode") { . "$(code --locate-shell-integration-path pwsh)" }
+```
+
+### Verify Integration
+
+Check if shell integration is active:
+
 ```powershell
 # Check environment variable (PowerShell 7+ only)
 if ($env:VSCODE_SHELL_INTEGRATION) {