feature: add GET /health for bcgov Tier 2 smoke

## Problem
Smoke test for Tier 2 on bcgov — coding agent assign + Azure LLM review.

## Outcome
GET /health returns 200 with `{"status":"ok"}`.

## Spec reference
spec/features/example-happy-path.feature

## Acceptance criteria
Given the service in src/
When GET /health
Then status 200 and JSON status ok

## Constraints
- Draft PR only; do not merge
- Update docs/pr-evidence.md

Start in src/ and review spec/features/example-happy-path.feature to locate the service entry point and existing route conventions. Add the GET /health behavior described in the acceptance criteria, then update docs/pr-evidence.md. Done means the endpoint returns HTTP 200 with {"status":"ok"} and the work is submitted as a draft PR.

Written by the indexing model from the issue text.