Add unified project Page and strengthen OpenAPI validation

[DataTideHH]

Summary

• add a compact GitHub Pages landing page under docs/
• apply the established DataTideHH Cayman design with Hanseblau, Tide-Teal, paper-white surfaces, responsive tables and automatic dark mode
• connect the repository README to the project site and make the evidence section more precise
• add semantic OpenAPI 3.1 validation through openapi-spec-validator
• compare the documented OpenAPI paths with the actual Flask runtime routes
• keep the page focused on Data/BI, controlled ingestion, data quality and process observability

Validation target

• all existing Python 3.12 tests remain green on Ubuntu and Windows
• the OpenAPI document is validated as an OpenAPI specification, not only parsed as YAML
• the OpenAPI path set matches the registered Flask routes
• the Pages source remains main + /docs, consistent with the other DataTideHH project sites

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Compare documented HTTP methods as well as paths

When a new HTTP method is registered on an existing URL, such as POST /api/v1/countries, runtime_paths remains unchanged and this test passes even if the OpenAPI document omits the operation. Since an operation is identified by both path and method, compare normalized (path, method) pairs while excluding Flask's implicit HEAD and OPTIONS methods so the claimed runtime-route coverage catches incomplete contracts.

Useful? React with 👍 / 👎.

[chatgpt-codex-connector]

Darken light-mode links to preserve text contrast

In the default light color scheme, #0b92b6 has only about a 3.46:1 contrast ratio against the page's #fafaf7 background (and 3.62:1 against white table surfaces). The normal 17px link text therefore falls below the WCAG AA 4.5:1 threshold, making links difficult to read for low-vision users; use a darker link color in light mode while retaining the brighter dark-mode override.

Useful? React with 👍 / 👎.