test: publish task-aware benchmark medians

[SarthakWade]

Closes #38

Summary

• add task-aware inspect --context actions --task calls to the cold and warm Headless benchmark workflows
• collect repeat runs as strict NDJSON and publish a versioned JSON document with every raw sample and per-metric medians
• refresh the canonical Linux ARM64 snapshot from five fresh containers per case
• document the mixed measured result: Headless warm has the smallest workflow surface and lowest median CPU, while Puppeteer is fastest and has the lowest median peak memory
• add deterministic regression coverage and mark backlog item D5 complete

Result artifact

packages/benchmark-results/results.json records:

• 20 raw samples across four workflows
• median wall time, CPU time, peak memory, artifact bytes, workflow bytes, and estimated tokens
• generation time, Linux container architecture, repeat count, aggregation method, generator, method document, and task-aware status

The default benchmark output is canonical; a second CLI argument writes an independent comparison artifact.

Hardening

• reject zero, non-numeric, and excessive repeat counts before Docker work begins
• reject malformed JSON, unknown cases, unexpected fields, unsafe numeric metrics, incomplete case sets, and inconsistent source-size metrics
• write results atomically through a private temporary file, publish as mode 0644, and preserve an existing result on validation failure
• use a run-specific Docker image tag and remove it on success, interruption, or failure
• run aggregation inside the benchmark image so Docker remains the only host dependency
• retain all raw samples so outliers remain visible instead of being hidden by aggregation

Verification

• ./apps/headless/benchmark.sh 5 completed 20 fresh containers and generated the committed snapshot
• ./apps/headless/benchmark.sh 1 /private/tmp/headless-benchmark-smoke.json verified custom output, permissions, and Docker image cleanup
• a second four-container smoke run verified containerized aggregation with no host Node dependency
• shellcheck apps/headless/benchmark.sh apps/headless/Tests/Benchmarks/headless.sh apps/headless/Tests/Benchmarks/headless_warm.sh
• pnpm test
• pnpm test:runtime
• pnpm --filter @headless/web lint
• pnpm --filter @headless/web build
• HEADLESS_VERSION=0.0.38 ./apps/headless/build.sh
• pnpm test:e2e:mac
• pnpm test:e2e:linux
• git diff --check