Initialize the current directory as an IWE project.

Creates the .iwe/ directory with a default config.toml file. This establishes
the directory as an IWE-managed knowledge base, enabling all CLI commands and
LSP server features.

Configuration options in .iwe/config.toml:
- library.path: Subdirectory containing markdown files (default: "")
- library.date_format: Date format for templates (default: "%Y-%m-%d")
- markdown.refs_extension: Extension appended to written markdown links (default: empty)
- completion.link_format: Link style - "markdown" or "wiki"

Prerequisites:
- The .iwe directory must not already exist in the current location
