docs: simplify bilingual READMEs and preserve implementation guides

[tappe9]

Summary

Closes #74.

• Reduce the English/Japanese READMEs to purpose, verified results, interpretation, one container-only local example and deeper documentation links.
• Move existing setup, runtime, pinned-version and acceptance guidance into docs/LOCAL-DEVELOPMENT.md and docs/LOCAL-DEVELOPMENT.ja.md; retain the dedicated implementation guides.
• Explain host prerequisites, shared port use and destructive Compose/Make cleanup explicitly.
• Keep registry/CI/cohort/publication/release boundaries separate. Correct the canonical guide's stale claim that the September 15 Waitress report is still the latest publication.
• Add regression coverage for bilingual navigation, identical quick-start commands, cleanup warnings, relocated guidance and local links/anchors.

The generated result blocks, all nine tracked results/** files (JSON/history/charts), runtime code, pins, registry and workflows are unchanged. No official measurement, diagnostic dispatch, publication, cohort activation or old-CI status repair is included.

Verification

• New documentation tests were run before the edits and failed on missing guide/navigation/quick-start behavior; the stale-publication regression also failed before its wording fix.
• All 11 documentation/navigation tests pass.
• make test-registry, python3 -m benchmark.generate_readme --check, pinned Ruff 0.16.5 lint/changed-file format checks and git diff --check pass.
• Independently verified that both generated README blocks and all nine tracked result files are byte-identical to base ea6a796.
• Independent review found no remaining actionable issues after formatting the new test file.

Local verification limits

The container-only example was reviewed against Compose but could not be executed locally because Docker is unavailable. make test stops at the Compose parity prerequisite. The broader benchmark suite passes 262/263 tests; the existing Go Echo native test fails because this environment's /usr/bin/go is not the Go language toolchain (Unknown option: mod). Site checks pass all 24 Python tests and 27/28 JavaScript tests; the real-browser test cannot create its Chromium sandbox socket (Operation not permitted). These are disclosed limits, not a local full-suite pass.

Exact-head CI 36897586208, attempt 1 completed successfully for 168ed1692b8f341bc13fb65529c0c375e23908a3: all 13 jobs, including required, passed. This covers the shared documentation/registry/site checks, all implementation acceptance and focused contracts, and the normal non-publishing smoke job.

Merge verification

Squash-merged with maintainer approval as ca10dfc86b7a1a42cf4c8aa9142adb3e76db169b. Its tree exactly matches the reviewed PR head. Issue #74 closed as completed.

Post-merge CI 36899400163, attempt 1 passed all 13 jobs, including required. Automatic Pages 36900530405 completed successfully for the same merge source. No official benchmark or diagnostic was dispatched, and no unrelated CI run was changed.