Add CLI export with interactive menu and streaming XML for large packages

[Copilot]

Extends CLI to match Blazor feature parity with optimizations for large package files using streaming XML parsing to avoid loading entire documents into memory.

Changes

CLI Infrastructure

• Interactive menu mode - Launch by passing package file path alone, provides guided navigation through content exploration and export wizards
• Command-line mode - list and export commands with --type, --format, --output, --properties options for automation

List Commands

• list --type [content|content-types|media|categories|audiences] - Displays items with summary statistics (counts by type, language, properties, etc.)
• Supports all package artifact types available in Blazor version

Export Functionality

• CSV/JSON export for content (with custom property selection), content-types, and categories
• Interactive mode shows available properties before export to guide selection
• Auto-detects large packages (>10k items) and switches to streaming mode

Performance Optimization

• StreamingPackageParser - XmlReader-based parser that yields items incrementally instead of loading full XDocument
• Exposed ZipArchive property on ZipPackage for streaming access
• Progress indicators every 1,000 items for long-running exports

Example Usage

# Interactive mode
./CLI.exe package.episerverdata

# Command-line list
./CLI.exe list --type content package.episerverdata

# Command-line export with streaming (auto-enabled for large files)
./CLI.exe export package.episerverdata \
  --type content \
  --format csv \
  --output out.csv \
  --properties PageName,PageTypeName,PageLink

Dependencies

• System.CommandLine 2.0.0-beta4 - Argument parsing
• CsvHelper 33.0.1 - CSV serialization
• System.Text.Json 8.0.5 - Streaming JSON writer

Original prompt

---

This section details on the original issue you should resolve

<issue_title>CLI Export</issue_title>
<issue_description>Extend the CLI to support all the features as the blazor version, but also scale so it can work with very large package files (using tricks like avoid loading all xml into one xdocument).
If started with only a filename of a package it should offer a menu with options of what to do - like list content, content types, media, categories and so on.
All lists should also include summaries.

It should also have the possibility to export content to csv or json, where the user provides a list of properties to export and a filename to export to.
These things should be possible both using the CLI menu (where there should also be helpful information along the way like which properties are available and so on), or purely through commandline parameters.

Use as much shared code from the Core package as possible.

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes CLI Export #17

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