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/google.golang.org/protobuf/reflect/protoregistry/registry.go

@@ -95,7 +95,7 @@ type Files struct {
 	// multiple files. Only top-level declarations are registered.
 	// Note that enum values are in the top-level since that are in the same
 	// scope as the parent enum.
-	descsByName map[protoreflect.FullName]interface{}
+	descsByName map[protoreflect.FullName]any
 	filesByPath map[string][]protoreflect.FileDescriptor
 	numFiles    int
 }
@@ -117,7 +117,7 @@ func (r *Files) RegisterFile(file protoreflect.FileDescriptor) error {
 		defer globalMutex.Unlock()
 	}
 	if r.descsByName == nil {
-		r.descsByName = map[protoreflect.FullName]interface{}{
+		r.descsByName = map[protoreflect.FullName]any{
 			"": &packageDescriptor{},
 		}
 		r.filesByPath = make(map[string][]protoreflect.FileDescriptor)
@@ -485,7 +485,7 @@ type Types struct {
 }
 
 type (
-	typesByName         map[protoreflect.FullName]interface{}
+	typesByName         map[protoreflect.FullName]any
 	extensionsByMessage map[protoreflect.FullName]extensionsByNumber
 	extensionsByNumber  map[protoreflect.FieldNumber]protoreflect.ExtensionType
 )
@@ -570,7 +570,7 @@ func (r *Types) RegisterExtension(xt protoreflect.ExtensionType) error {
 	return nil
 }
 
-func (r *Types) register(kind string, desc protoreflect.Descriptor, typ interface{}) error {
+func (r *Types) register(kind string, desc protoreflect.Descriptor, typ any) error {
 	name := desc.FullName()
 	prev := r.typesByName[name]
 	if prev != nil {
@@ -841,7 +841,7 @@ func (r *Types) RangeExtensionsByMessage(message protoreflect.FullName, f func(p
 	}
 }
 
-func typeName(t interface{}) string {
+func typeName(t any) string {
 	switch t.(type) {
 	case protoreflect.EnumType:
 		return "enum"
@@ -854,7 +854,7 @@ func typeName(t interface{}) string {
 	}
 }
 
-func amendErrorWithCaller(err error, prev, curr interface{}) error {
+func amendErrorWithCaller(err error, prev, curr any) error {
 	prevPkg := goPackage(prev)
 	currPkg := goPackage(curr)
 	if prevPkg == "" || currPkg == "" || prevPkg == currPkg {
@@ -863,7 +863,7 @@ func amendErrorWithCaller(err error, prev, curr interface{}) error {
 	return errors.New("%s\n\tpreviously from: %q\n\tcurrently from:  %q", err, prevPkg, currPkg)
 }
 
-func goPackage(v interface{}) string {
+func goPackage(v any) string {
 	switch d := v.(type) {
 	case protoreflect.EnumType:
 		v = d.Descriptor()