Add end-to-end acceptance on real collector containers, and cost/accuracy experiment tooling

[zzylol]

Part 8 of the RFC 0001 stack: the end-to-end acceptance, plus the tooling for experiments 1 and 2. The measured results come in the last PR of the stack.

deploy/telemetry-functions/acceptance.py

Runs all four use cases on the real collector containers (generators, branches, merge, detector, exact baseline, Prometheus, Loki). It checks the sketch answers against the exact ground truth through Prometheus and Loki, prints PASS or FAIL per check, and exits non-zero on any failure.

To keep it to a few minutes per use case, time is scaled down 6×: 10-second windows, a 2-second grace (raised back to the deployed 5 s in #31, after the first real CI run showed sketches arriving later than 2 s on a shared 4-CPU runner), changes at second 100, and growth 6× faster. Rules counted in windows (baselines, thresholds) are as deployed. Comparisons are pinned to one window answered by both methods, with PromQL's @ modifier.

Result on a 56-core x86 server: 25/25 checks passed.

Use case	Checks (all passed)
all four	7/7 stages up; 400,000 points in every window, the full offered rate; sketch and exact windows hold identical point counts
latency	exact p50/p99 inside the sketch's bound: 40/40
cardinality	sketch and exact give every key the same class (user.id identifier-like, k8s.pod.name growing, http.route and http.method stable); distinct error ≤ 1.13%; class events in Loki
drift	route-3 drift detected by both methods (KS 0.33); no other route flagged; drift event in Loki
top-k	/new/hot-route in both top-10s; recall@10 = 1.00; novelty event in Loki

Informational, not a pass condition: with 10-second windows, the p99 relative error for routes with ≥ 20,000 points reached 12.8%. That is KLL's rank error in a log-normal tail (see #25).

experiments.py and report_experiments.py

• inline-cost: branch CPU with and without each function, over offered rates. In this run the exact stage only counts points, so it cannot throttle the branch.
• accuracy-size: error against exact as KLL k and Count-Min width change, with the bytes merge receives per window.
• The answer paths report asap_answer_delay: seconds from a window's end to its answers.
• report_experiments.py turns the CSVs into a Markdown report with tables and a figure.

Also includes PIPELINES and the published Loki port in compose, run.sh --build-only, and a README covering every use case.

cargo fmt --check, cargo clippy ... -D warnings and cargo test --features otap-engine,stream-benchmark pass at this PR's head.