feat: ship R16.3 cockpit and repository closure

[eimyroot]

Summary

Close the current HOWEDO repository milestone with a runnable operator surface, a professional English-facing repository entry point, and explicit scaffold hygiene/architecture rules.

Scope

Operator surface

• serve a self-contained HOWEDO Continuity Cockpit at / and /cockpit from the existing FastAPI process;
• live /health status and real /v1/continuity/check demo execution;
• browser hardening headers: CSP, nosniff, frame denial, no-referrer;
• add howedo-cockpit CLI with loopback-first default;
• add hardened loopback Docker Compose profile.

Repository presentation

• replace the long-form front page with a concise English product README;
• add a canonical HOWEDO SVG banner to the top of the GitHub-visible README;
• add architecture diagram, quick-start, production boundary, documentation map, and quality gates.

Scaffold / hygiene

• add docs/ARCHITECTURE.md with layer ownership, dependency direction, placement policy, cockpit boundary, and ADR triggers;
• add deterministic tracked-file hygiene checker and dedicated GitHub Actions workflow;
• add .editorconfig;
• keep the continuity kernel vendor-neutral and keep presentation logic out of kernel semantics.

Verification coverage

• add cockpit route/render/header tests;
• existing CI continues to run Ruff, pytest, release-candidate build/clean-install/SBOM/release-bundle replay on Python 3.12 and 3.13;
• existing container workflow remains the deployable OCI verification path.

Risk and security

Risk class: behavior + presentation + repository hygiene.

The cockpit intentionally does not add a second frontend toolchain, external JS/CDN dependency, IAM layer, or new continuity semantics. Local launcher and Compose bind to 127.0.0.1 by default. Production exposure still requires explicit network/TLS/authentication controls outside the cockpit.

No secrets or personal data introduced.

Rollback

Revert commit 3bd79c8885f9977a60dfdefc79fd0915c5477e8a. Existing /health, /ready, /v1/continuity/check, and /v1/recovery/check semantics are otherwise preserved.

Evidence checklist

• Diff is focused on the R16.3 closure milestone.
• New browser behavior has tests.
• Documentation states pre-1.0 / non-audited production boundaries explicitly.
• No generated runtime state, secrets, or personal data are committed.
• Required GitHub Actions checks pass on this exact head.