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/metric/asyncfloat64.go

@@ -1,16 +1,5 @@
 // Copyright The OpenTelemetry Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
+// SPDX-License-Identifier: Apache-2.0
 
 package metric // import "go.opentelemetry.io/otel/metric"
 
@@ -50,7 +39,7 @@ type Float64ObservableCounter interface {
 }
 
 // Float64ObservableCounterConfig contains options for asynchronous counter
-// instruments that record int64 values.
+// instruments that record float64 values.
 type Float64ObservableCounterConfig struct {
 	description string
 	unit        string
@@ -108,7 +97,7 @@ type Float64ObservableUpDownCounter interface {
 }
 
 // Float64ObservableUpDownCounterConfig contains options for asynchronous
-// counter instruments that record int64 values.
+// counter instruments that record float64 values.
 type Float64ObservableUpDownCounterConfig struct {
 	description string
 	unit        string
@@ -117,7 +106,9 @@ type Float64ObservableUpDownCounterConfig struct {
 
 // NewFloat64ObservableUpDownCounterConfig returns a new
 // [Float64ObservableUpDownCounterConfig] with all opts applied.
-func NewFloat64ObservableUpDownCounterConfig(opts ...Float64ObservableUpDownCounterOption) Float64ObservableUpDownCounterConfig {
+func NewFloat64ObservableUpDownCounterConfig(
+	opts ...Float64ObservableUpDownCounterOption,
+) Float64ObservableUpDownCounterConfig {
 	var config Float64ObservableUpDownCounterConfig
 	for _, o := range opts {
 		config = o.applyFloat64ObservableUpDownCounter(config)
@@ -165,7 +156,7 @@ type Float64ObservableGauge interface {
 }
 
 // Float64ObservableGaugeConfig contains options for asynchronous counter
-// instruments that record int64 values.
+// instruments that record float64 values.
 type Float64ObservableGaugeConfig struct {
 	description string
 	unit        string
@@ -224,7 +215,7 @@ type Float64Observer interface {
 }
 
 // Float64Callback is a function registered with a Meter that makes
-// observations for a Float64Observerable instrument it is registered with.
+// observations for a Float64Observable instrument it is registered with.
 // Calls to the Float64Observer record measurement values for the
 // Float64Observable.
 //
@@ -250,12 +241,16 @@ type float64CallbackOpt struct {
 	cback Float64Callback
 }
 
-func (o float64CallbackOpt) applyFloat64ObservableCounter(cfg Float64ObservableCounterConfig) Float64ObservableCounterConfig {
+func (o float64CallbackOpt) applyFloat64ObservableCounter(
+	cfg Float64ObservableCounterConfig,
+) Float64ObservableCounterConfig {
 	cfg.callbacks = append(cfg.callbacks, o.cback)
 	return cfg
 }
 
-func (o float64CallbackOpt) applyFloat64ObservableUpDownCounter(cfg Float64ObservableUpDownCounterConfig) Float64ObservableUpDownCounterConfig {
+func (o float64CallbackOpt) applyFloat64ObservableUpDownCounter(
+	cfg Float64ObservableUpDownCounterConfig,
+) Float64ObservableUpDownCounterConfig {
 	cfg.callbacks = append(cfg.callbacks, o.cback)
 	return cfg
 }