Add configuration to exclude files/folders from workspace-to-volume mapping

[nezhar]

Background

Currently the CLI maps the entire current workspace into the container volume by default. This causes large or unnecessary directories (for example, node_modules) to be included in the volume mapping and copied/mounted.

Goal

Add a new configuration option that lets users specify a list of files and directories (and optionally glob patterns) to exclude from the default workspace-to-volume mapping.

Requirements / Acceptance criteria

• Default behavior remains unchanged: the current workspace is mapped by default if no excludes are configured.
• Provide a new configuration key (example name: volume.exclude or mapping.excludes) that accepts a list of path strings and/or glob patterns.
• Excludes should be applied relative to the workspace root by default.
• Support common patterns like node_modules, .git, build/, dist/**, **/node_modules.
• Exclude patterns must not break other mapping features (preserve symlinks behavior and file permissions as currently implemented).
• Implement clear precedence rules if both include and exclude logic exist (excludes should take precedence when a path matches both rules).
• Document the new option in the README and configuration reference with examples.

Examples

YAML config example:

mapping:
excludes:
- node_modules
- .git
- dist/**

CLI flag example (if applicable):

--exclude=node_modules --exclude=.git

Notes

• Consider whether to support both glob patterns and plain relative paths; prefer glob support for flexibility.
• Consider adding sensible default excludes (optional) or leave the list empty by default to preserve current behavior.

Tasks

• Add config parsing for the new key.
• Wire exclude logic into the file-to-volume mapping routine.
• Add unit tests covering typical patterns and edge cases.
• Add documentation and changelog entry.