Add sudo-safe pycache redirect and ps-based process discovery fallback

[wwulfric]

Motivation

• Ensure Peeka avoids writing root-owned bytecode caches into user virtualenvs when launched under sudo by redirecting sys.pycache_prefix to a safe temporary prefix.
• Provide process discovery on platforms without /proc (e.g., macOS) by falling back to ps output parsing.

Description

• Add import-time policy in peeka/__init__.py with _running_under_sudo, _sudo_pycache_prefix, and _configure_sudo_bytecode_policy to set sys.pycache_prefix when running under sudo, guardable via PEEKA_DISABLE_SUDO_PYCACHE_REDIRECT and configurable via PEEKA_SUDO_PYCACHE_PREFIX.
• Refactor peeka/core/processes.py to return a ps-based fallback by adding _discover_python_processes_with_ps, _python_process_from_fields, and using subprocess/shlex to parse ps -axo pid=,comm=,command= when /proc is unavailable.
• Adjust _read_python_process to centralize construction of PythonProcess objects and carry created_at through the new helper.
• Add new unit tests in tests/test_import_policy.py covering the sudo bytecode cache redirection behavior and extend tests/test_processes.py with tests for the ps fallback and related filtering.

Testing

• Ran the new import-time policy tests in tests/test_import_policy.py which exercise importlib.reload(peeka) under mocked geteuid and environment variables, and they passed.
• Executed the updated process discovery tests in tests/test_processes.py including test_discover_python_processes_falls_back_to_ps_without_proc and test_discover_python_processes_ps_fallback_excludes_current_process, and they passed.
• Overall unit test run for the modified files succeeded.

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Codex Task