change: Implement 1: Bootstrap the toolkit tree, project config and initial dependency lock

Bootstrapped the repository-root toolkit tree required by the facade.

- `tools/__init__.py`: minimal importable package exposing `__version__` only.
- `tools/example.py`: offline CLI (`python -m tools.example REQUEST`) that loads and validates a JSON request document with a validate-only `dry_run` semantics, prints exactly one structured JSON envelope (sorted keys) and fixes the status/exit vocabulary now (0 ok, 1 invalid request document, 2 usage error). `--help` supported.
- `examples/input.json`: canonical offline validate-only request document.
- `tests/test_example.py`: focused tests for the smoke command, envelope shape, request-document validation, `--help`, and the module entrypoint (13 tests).
- `pyproject.toml`: project metadata, setuptools build backend with `packages = ["tools"]`, `dev` extra with `pytest>=8.0`, pytest options `pythonpath=["."]` / `testpaths=["tests"]` so the repository root is importable.
- `uv.lock`: created through the supported dependency update operation for the `tools` component; pinned only from the approved dependency mirror (no public-index fallbacks, no credentials).
- `.gitignore` / `.env.example`: keep build artifacts out of the tree and document that no environment variables are required.

Note: `requires-python` was raised to `>=3.11` because the approved mirror only offers `exceptiongroup<1.0.0rc8`, which cannot satisfy pytest on Python <3.11; the prepared environment (CPython 3.12.3) and CI bootstrap interpreter satisfy this. No protected facade paths were modified.

Tests:
Ran the facade commands with the prepared environment (`.venv/bin/python`):
- `python -m compileall -q tools tests` -> OK (tools.validate)
- `python -m pytest -q` -> 13 passed (tools.test)
- `python -m tools.example examples/input.json` -> single JSON envelope, exit 0 (tools.smoke)
- `python -m tools.example --help` -> usage text, exit 0 (help-command)
Dependency lock/materialization performed via prepare_environment(component='tools', mode='update'): resolved + materialized, `uv.lock` written. Target branch `origin/task/1-task` is already an ancestor of HEAD, so the branch contains the current target.

Progress:
Created tools package (tools/__init__.py, tools/example.py), examples/input.json, tests/test_example.py, .gitignore, .env.example; updated pyproject.toml (metadata, setuptools packages, dev pytest extra, pytest pythonpath/testpaths, requires-python >=3.11 due to approved-mirror exceptiongroup constraint) and generated uv.lock via prepare_environment update. Facade validate/test/smoke and --help all pass locally.

Published by developer-agent through Tool Backend.

Closes #3

tools/__init__.py

@@ -0,0 +1,12 @@
+"""Importable toolkit package for the request-document CLI.
+
+The package intentionally exposes only its version metadata here; the
+executable behaviour lives in :mod:`tools.example` (and in the modules that
+later increments add).
+"""
+
+from __future__ import annotations
+
+__all__ = ["__version__"]
+
+__version__ = "0.1.0"