Enhancement: Add OpenCode CLI support (Invoke-OpenCodeTask)

[eigenverft]

User Story

As a user, I want to use the OpenCode CLI through this module, so that I can:

• Run OpenCode tasks from PowerShell scripts
• Use named sessions with OpenCode
• Have a consistent experience across all agent CLIs

Acceptance Criteria

Core Command

• Invoke-OpenCodeTask cmdlet added
• Supports -Prompt (mandatory, string)
• Supports -Directory / -Path
• Supports -SessionName / -Session
• Supports -AllowDangerous (default: $true)
• Supports -Json (default: $true)
• Supports -Model
• Supports -AddDir

Session Management

• Get-OpenCodeSession - List or get sessions
• Remove-OpenCodeSession - Remove a session
• Clear-OpenCodeSessions - Clear all sessions
• Session store: %LOCALAPPDATA%\Eigenverft.Manifested.Agent\sessions\named-opencode-sessions.json

Module Exports

• Add functions to FunctionsToExport in .psd1
• Add file to FileList in .psd1

Documentation

• Add to README.md Quick Start section
• Add to README.md Command Reference
• Add behavior notes for OpenCode

Example Usage

# One-shot task
Invoke-OpenCodeTask -Prompt "summarize this repository"

# Named session
Invoke-OpenCodeTask -Prompt "read the repo" -SessionName "opencode1"
Invoke-OpenCodeTask -Prompt "continue" -SessionName "opencode1"

# List sessions
Get-OpenCodeSession

Implementation Notes

• Follow existing pattern from Invoke-QwenTask / Invoke-GeminiTask
• OpenCode CLI likely uses similar headless/JSON output模式
• Check OpenCode CLI documentation for:
  • Command name (opencode?)
  • JSON output flag
  • Session/resume flags
  • Approval/sandbox flags

Tasks

• Research OpenCode CLI arguments and output formats
• Create Eigenverft.Manifested.Agent.InvokeOpenCodeTask.ps1
• Add session management functions
• Update module manifest
• Update README.md
• Test basic functionality