Rust treats `~` as a literal path character, not a home directory
shorthand. Several config resolution paths used `PathBuf::from()` on
user-provided strings without expanding `~` first, causing a literal
`~` folder to be created in the working directory.
Apply `shellexpand::tilde()` to all user-facing path inputs:
- ZEROCLAW_CONFIG_DIR env var (config/schema.rs, onboard/wizard.rs)
- ZEROCLAW_WORKSPACE env var (config/schema.rs, onboard/wizard.rs,
channels/matrix.rs)
- active_workspace.toml marker file config_dir (config/schema.rs)
The WhatsApp Web session_path was already correctly expanded via
shellexpand::tilde() in whatsapp_web.rs.
Closes#3417
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>