Add Unit 17: Performance story, tracing/profiling, testing
- Performance-Story.md: war-story narrative from the 9 Locust CSVs
in development/profiles/. Real numbers: baseline 5 RPS with 49%
failure to 1585 RPS / 0% failure at 1500 concurrent users.
Quantifies the OTel tax (~13% RPS, doubles p50) and the single-
core collapse (34x throughput loss). Calls out SQLite writer lock
as the remaining bottleneck.
- Tracing-and-Profiling.md: how to flip OpenTelemetry, Pyinstrument,
py-spy, memray, and snakeviz on and off. Documents the local OTel
collector compose file and extras groups. Production warning.
- Testing-and-CI.md: pytest layout, markers, default opt-outs, the
Locust stress recipe, project rules (tests for every feature,
never ship broken code, green before commit), and the no-scapy-
sniff-in-TestClient-lifespan rule.
