refactor: move command protocol schemas into Base

[codeforester]

Summary

• add a Base-owned command protocol adapter with all Base record schemas
• preserve BASE_COMMAND_PROTOCOL_V1 for the Bash peer while generic base-cli uses its neutral protocol header
• route Base Python producers and decoders through the consumer adapter
• document the ownership boundary and update the cross-language protocol test

Validation

• PYTHONPATH=/Users/rameshhp/work/base-cli-worktrees/27-protocol-schemas/lib/python:cli/python /Users/rameshhp/.base.d/base/.venv/bin/python -m pytest -q
• 931 passed, 1 skipped, 248 subtests passed
• full pylint suite passes
• focused command-protocol BATS suite: 9 passed
• git diff --check

Depends on basefoundry/base-cli#29.

Fixes #1843