Add knowledge-mapper run CLI subcommand (#10)

[DaviddeBest-TNO]

Closes #10.

What

Adds a typer-based knowledge-mapper CLI with one subcommand, run, that starts a Python-defined KnowledgeBase and replaces the usual asyncio.run(...) boilerplate:

knowledge-mapper run path/to/my_app.py:kb

The PATH:ATTR spec points at a Python file and the name of the KnowledgeBase variable inside it.

Behaviour

• Loads the file via importlib.util and retrieves the named attribute. The file's parent directory is added to sys.path so the module can import siblings just like python file.py.
• Runs the full async lifecycle: connect → register → start_handling_loop.
• On SIGINT / SIGTERM: cancels the handling task, then unregister + close run in finally, and the process exits cleanly.
• If start_handling_loop raises, unregister + close still run.

The issue's spec was written before the SDK switched to async; this implementation adapts the lifecycle accordingly (and adds close() to match the README lifecycle, as discussed).

Layout

• src/knowledge_mapper/cli.py — load_kb, run_kb, and the typer app with the run subcommand. A @app.callback() is added so the app keeps a subcommand structure (room for a future sparql subcommand, per the issue).
• pyproject.toml — adds typer>=0.15 dep and registers the knowledge-mapper = knowledge_mapper.cli:app console script.
• tests/test_cli.py — 9 behavior-focused tests written TDD-style covering load happy/sad paths, sibling imports, full lifecycle order, cleanup on error, graceful SIGINT shutdown, and an end-to-end typer CliRunner test.
• examples/10-cli.py — minimal KB definition with no asyncio.run / __main__ block, runnable via knowledge-mapper run 10-cli.py:kb.
• README.md, examples/README.md, CONTEXT.md updated.

Verification

• uv run pytest — 122 tests pass (113 existing + 9 new)
• uv run ruff check . — clean
• uv run knowledge-mapper --help and knowledge-mapper run --help render correctly
• Smoke-tested loading examples/10-cli.py via the loader — KI registered as expected