Wire petri --version into the CLI (Software Factory)

[markfreeman-dot-dev]

Closes #117.

What

Adds a top-level --version flag to the petri Typer app: eager callback that prints petri <version> (from petri.__version__) and exits 0, with no subcommand and no .petri/ project required. Includes a CliRunner test and a CHANGELOG entry.

Who — this PR was produced by an autonomous agent team on a DGX Spark (GB10), 100% local inference (Qwen3.6-35B-A3B via vLLM/llama-swap):

• Tech Lead analyzed the issue, produced the task artifact (correctly ruled no architect needed)
• Product Manager wrote acceptance criteria and edge cases
• Implementer wrote the code + test (commit 6182778) — first attempt
• DevOps/QA ran the targeted test, then the full suite: 526/526 passing
• Docs Engineer added the CHANGELOG entry (commit 7b6bce5)
• TPM enforced stop conditions at every gate (none triggered)

Total pipeline time: 5m20s, ~24k tokens, zero cloud calls. The full audit trail (per-agent YAML artifacts, timeline, token accounting) lives in the factory repo under evidence/artifacts/asjx/.

Human review requested — the factory stops at PR-ready by design.

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