Phase 2: Implement Execution Environment Abstraction (v0.3.0)

This commit implements Phase 2 of the CHORUS Task Execution Engine development plan,
providing a comprehensive execution environment abstraction layer with Docker
container sandboxing support.

## New Features

### Core Sandbox Interface
- Comprehensive ExecutionSandbox interface with isolated task execution
- Support for command execution, file I/O, environment management
- Resource usage monitoring and sandbox lifecycle management
- Standardized error handling with SandboxError types and categories

### Docker Container Sandbox Implementation
- Full Docker API integration with secure container creation
- Transparent repository mounting with configurable read/write access
- Advanced security policies with capability dropping and privilege controls
- Comprehensive resource limits (CPU, memory, disk, processes, file handles)
- Support for tmpfs mounts, masked paths, and read-only bind mounts
- Container lifecycle management with proper cleanup and health monitoring

### Security & Resource Management
- Configurable security policies with SELinux, AppArmor, and Seccomp support
- Fine-grained capability management with secure defaults
- Network isolation options with configurable DNS and proxy settings
- Resource monitoring with real-time CPU, memory, and network usage tracking
- Comprehensive ulimits configuration for process and file handle limits

### Repository Integration
- Seamless repository mounting from local paths to container workspaces
- Git configuration support with user credentials and global settings
- File inclusion/exclusion patterns for selective repository access
- Configurable permissions and ownership for mounted repositories

### Testing Infrastructure
- Comprehensive test suite with 60+ test cases covering all functionality
- Docker integration tests with Alpine Linux containers (skipped in short mode)
- Mock sandbox implementation for unit testing without Docker dependencies
- Security policy validation tests with read-only filesystem enforcement
- Resource usage monitoring and cleanup verification tests

## Technical Details

### Dependencies Added
- github.com/docker/docker v28.4.0+incompatible - Docker API client
- github.com/docker/go-connections v0.6.0 - Docker connection utilities
- github.com/docker/go-units v0.5.0 - Docker units and formatting
- Associated Docker API dependencies for complete container management

### Architecture
- Interface-driven design enabling multiple sandbox implementations
- Comprehensive configuration structures for all sandbox aspects
- Resource usage tracking with detailed metrics collection
- Error handling with retryable error classification
- Proper cleanup and resource management throughout sandbox lifecycle

### Compatibility
- Maintains backward compatibility with existing CHORUS architecture
- Designed for future integration with Phase 3 Core Task Execution Engine
- Extensible design supporting additional sandbox implementations (VM, process)

This Phase 2 implementation provides the foundation for secure, isolated task
execution that will be integrated with the AI model providers from Phase 1
in the upcoming Phase 3 development.

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

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

vendor/go.opentelemetry.io/otel/semconv/v1.37.0/MIGRATION.md

@@ -0,0 +1,41 @@
+<!-- Generated. DO NOT MODIFY. -->
+# Migration from v1.36.0 to v1.37.0
+
+The `go.opentelemetry.io/otel/semconv/v1.37.0` package should be a drop-in replacement for `go.opentelemetry.io/otel/semconv/v1.36.0` with the following exceptions.
+
+## Removed
+
+The following declarations have been removed.
+Refer to the [OpenTelemetry Semantic Conventions documentation] for deprecation instructions.
+
+If the type is not listed in the documentation as deprecated, it has been removed in this version due to lack of applicability or use.
+If you use any of these non-deprecated declarations in your Go application, please [open an issue] describing your use-case.
+
+- `ContainerRuntime`
+- `ContainerRuntimeKey`
+- `GenAIOpenAIRequestServiceTierAuto`
+- `GenAIOpenAIRequestServiceTierDefault`
+- `GenAIOpenAIRequestServiceTierKey`
+- `GenAIOpenAIResponseServiceTier`
+- `GenAIOpenAIResponseServiceTierKey`
+- `GenAIOpenAIResponseSystemFingerprint`
+- `GenAIOpenAIResponseSystemFingerprintKey`
+- `GenAISystemAWSBedrock`
+- `GenAISystemAnthropic`
+- `GenAISystemAzureAIInference`
+- `GenAISystemAzureAIOpenAI`
+- `GenAISystemCohere`
+- `GenAISystemDeepseek`
+- `GenAISystemGCPGemini`
+- `GenAISystemGCPGenAI`
+- `GenAISystemGCPVertexAI`
+- `GenAISystemGroq`
+- `GenAISystemIBMWatsonxAI`
+- `GenAISystemKey`
+- `GenAISystemMistralAI`
+- `GenAISystemOpenAI`
+- `GenAISystemPerplexity`
+- `GenAISystemXai`
+
+[OpenTelemetry Semantic Conventions documentation]: https://github.com/open-telemetry/semantic-conventions
+[open an issue]: https://github.com/open-telemetry/opentelemetry-go/issues/new?template=Blank+issue

vendor/go.opentelemetry.io/otel/semconv/v1.37.0/README.md

@@ -0,0 +1,3 @@
+# Semconv v1.37.0
+
+[![PkgGoDev](https://pkg.go.dev/badge/go.opentelemetry.io/otel/semconv/v1.37.0)](https://pkg.go.dev/go.opentelemetry.io/otel/semconv/v1.37.0)

vendor/go.opentelemetry.io/otel/semconv/v1.37.0/doc.go

@@ -0,0 +1,9 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+// Package semconv implements OpenTelemetry semantic conventions.
+//
+// OpenTelemetry semantic conventions are agreed standardized naming
+// patterns for OpenTelemetry things. This package represents the v1.37.0
+// version of the OpenTelemetry semantic conventions.
+package semconv // import "go.opentelemetry.io/otel/semconv/v1.37.0"

vendor/go.opentelemetry.io/otel/semconv/v1.37.0/error_type.go

@@ -0,0 +1,31 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package semconv // import "go.opentelemetry.io/otel/semconv/v1.37.0"
+
+import (
+	"fmt"
+	"reflect"
+
+	"go.opentelemetry.io/otel/attribute"
+)
+
+// ErrorType returns an [attribute.KeyValue] identifying the error type of err.
+func ErrorType(err error) attribute.KeyValue {
+	if err == nil {
+		return ErrorTypeOther
+	}
+	t := reflect.TypeOf(err)
+	var value string
+	if t.PkgPath() == "" && t.Name() == "" {
+		// Likely a builtin type.
+		value = t.String()
+	} else {
+		value = fmt.Sprintf("%s.%s", t.PkgPath(), t.Name())
+	}
+
+	if value == "" {
+		return ErrorTypeOther
+	}
+	return ErrorTypeKey.String(value)
+}

vendor/go.opentelemetry.io/otel/semconv/v1.37.0/exception.go

@@ -0,0 +1,9 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package semconv // import "go.opentelemetry.io/otel/semconv/v1.37.0"
+
+const (
+	// ExceptionEventName is the name of the Span event representing an exception.
+	ExceptionEventName = "exception"
+)

vendor/go.opentelemetry.io/otel/semconv/v1.37.0/schema.go

@@ -0,0 +1,9 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package semconv // import "go.opentelemetry.io/otel/semconv/v1.37.0"
+
+// SchemaURL is the schema URL that matches the version of the semantic conventions
+// that this package defines. Semconv packages starting from v1.4.0 must declare
+// non-empty schema URL in the form https://opentelemetry.io/schemas/<version>
+const SchemaURL = "https://opentelemetry.io/schemas/1.37.0"