feat: Add Docker secrets support for ResetData API key

This commit introduces secure Docker secrets integration for the ResetData
API key, enabling CHORUS to read sensitive configuration from mounted secret
files instead of environment variables.

## Key Changes:

**Security Enhancement:**
- Modified `pkg/config/config.go` to support reading ResetData API key from
  Docker secret files using `getEnvOrFileContent()` pattern
- Enables secure deployment with `RESETDATA_API_KEY_FILE` pointing to
  mounted secret file instead of plain text environment variables

**Container Deployment:**
- Added `Dockerfile.simple` for optimized Alpine-based deployment using
  pre-built static binaries (chorus-agent)
- Updated `docker-compose.yml` with proper secret mounting configuration
- Fixed container binary path to use new `chorus-agent` instead of deprecated
  `chorus` wrapper

**WHOOSH Integration:**
- Critical for WHOOSH wave-based auto-scaling system integration
- Enables secure credential management in Docker Swarm deployments
- Supports dynamic scaling operations while maintaining security standards

## Technical Details:

The ResetData configuration now supports both environment variable fallback
and Docker secrets:
```go
APIKey: getEnvOrFileContent("RESETDATA_API_KEY", "RESETDATA_API_KEY_FILE")
```

This change enables CHORUS to participate in WHOOSH's wave-based scaling
architecture while maintaining production-grade security for API credentials.

## Testing:

- Verified successful deployment in Docker Swarm environment
- Confirmed CHORUS agent initialization with secret-based configuration
- Validated integration with BACKBEAT and P2P networking components

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

pkg/config/config.go

@@ -179,7 +179,7 @@ func LoadFromEnvironment() (*Config, error) {
 			},
 			ResetData: ResetDataConfig{
 				BaseURL: getEnvOrDefault("RESETDATA_BASE_URL", "https://models.au-syd.resetdata.ai/v1"),
-				APIKey:  os.Getenv("RESETDATA_API_KEY"),
+				APIKey:  getEnvOrFileContent("RESETDATA_API_KEY", "RESETDATA_API_KEY_FILE"),
 				Model:   getEnvOrDefault("RESETDATA_MODEL", "meta/llama-3.1-8b-instruct"),
 				Timeout: getEnvDurationOrDefault("RESETDATA_TIMEOUT", 30*time.Second),
 			},
@@ -363,3 +363,17 @@ func SaveConfig(cfg *Config, configPath string) error {
 	// For containers, configuration is environment-based, so this is a no-op
 	return nil
 }
+
+// LoadRuntimeConfig loads configuration with runtime assignment support
+func LoadRuntimeConfig() (*RuntimeConfig, error) {
+	// Load base configuration from environment
+	baseConfig, err := LoadFromEnvironment()
+	if err != nil {
+		return nil, fmt.Errorf("failed to load base configuration: %w", err)
+	}
+
+	// Create runtime configuration manager
+	runtimeConfig := NewRuntimeConfig(baseConfig)
+
+	return runtimeConfig, nil
+}