[codeforester]

Summary

Closes #242.

• Add the reviewed docs/api-manifest.json with core, integration, advanced, and provisional tiers for every facade export.
• Add the small base_cli.core lifecycle surface for new applications while preserving the broad 0.x compatibility facade.
• Add manifest validation and contract tests so new exports require an explicit tier classification.
• Document the migration path, optional-integration boundary, and API manifest in the README and API stability guide.
• Regenerate the public API reference and include the manifest in the contracts gate.

Validation

• UV_CACHE_DIR=/private/tmp/base-cli-uv-cache uv run python scripts/validate_api_manifest.py
• UV_CACHE_DIR=/private/tmp/base-cli-uv-cache uv run pytest -q tests/test_api_manifest.py tests/test_public_api.py tests/test_api_stability.py
• UV_CACHE_DIR=/private/tmp/base-cli-uv-cache uv run --extra quality ./tests/full_validate.sh --gate style
• UV_CACHE_DIR=/private/tmp/base-cli-uv-cache uv run --extra dev --extra typer --extra quality ./tests/full_validate.sh --gate contracts
• git diff --check

The compatibility facade remains unchanged for existing 0.x consumers; this PR establishes the reviewed 1.0 segmentation and recommended starting surface without requiring optional Typer, Rich, or OpenTelemetry packages for the core.