Extract basilisk.os + shell/sshd/sftp into ic-basilisk-os package

[deucalioncodes]

Summary

Extract basilisk.os (canister-side OS layer) and the client-side shell tools (exec, shell, sshd, sftp) into a new standalone PyPI package: ic-basilisk-os.

This continues the modularization started in #31 and follows the same pattern as ic-python-db and ic-python-logging.

Motivation

ic-basilisk should be a minimal CDK (@query, @update, ic.*, build, new). The OS layer (entities, wallet, tasks, crypto, FX, vetkeys) and client tools (shell, SFTP, SSHD) are optional and should be a separate package that users install only if needed.

What moves to ic-basilisk-os

Source modules

• basilisk/os/ → ic_basilisk_os/ (entities, wallet, task_manager, execution, crypto, vetkeys, fx, tokens, status)
• basilisk/shell.py → ic_basilisk_os/shell.py
• basilisk/sftp.py → ic_basilisk_os/sftp.py
• basilisk/sshd.py → ic_basilisk_os/sshd.py

CLI commands

• basilisk exec, basilisk shell, basilisk sshd move to ic-basilisk-os
• basilisk CLI keeps new and build only
• Backward compat: basilisk shell etc. still work by forwarding to ic_basilisk_os (with helpful error if not installed)

Tests (~390K+ of test code)

• test_shell.py, test_sftp.py, test_tasks.py, test_wallet.py, test_wallet_hook.py, test_wallet_shell.py, test_crypto.py, test_vetkeys.py, test_fx.py, test_filesystem.py, test_db_shell.py, test_guards.py
• conftest.py (shared fixtures)
• test_canister/ and fixtures/

Stays in ic-basilisk

• basilisk/__init__.py (CDK types, decorators, ic class)
• basilisk/cli.py (new, build commands + thin forwarding)
• basilisk/__main__.py (WASM compiler)
• basilisk/compiler/, basilisk/canisters/, basilisk/templates/
• test_bundle.py, integration/ tests

Import changes in moved files

• from basilisk.db import ... → from ic_python_db import ...
• from basilisk.logging import ... → from ic_python_logging import ...
• from basilisk.shell import ... → from .shell import ...
• from basilisk import Async, Principal, ic → stays (CDK)

Dependencies

• ic-basilisk: install_requires=[] (no required deps)
• ic-basilisk-os: install_requires=["ic-basilisk", "ic-python-db", "ic-python-logging"], extras_require={"shell": ["asyncssh"]}

Backward compatibility

• basilisk/os/__init__.py becomes thin re-export: from ic_basilisk_os import *
• basilisk CLI forwards exec/shell/sshd to ic_basilisk_os with error if not installed

Relates to #31