chore: add AGENTS.md (#170)

Co-authored-by: Jake Van Vorhis <83739412+jakedoublev@users.noreply.github.com>

Author: strantalis

AGENTS.md

@@ -0,0 +1,41 @@
+# Repository Guidelines
+
+## Project Structure & Module Organization
+
+- `docs/`: Documentation content in Markdown/MDX (for example `docs/getting-started/index.mdx`).
+- `src/`: Docusaurus site code (React/TypeScript), including OpenAPI tooling in `src/openapi/`.
+- `specs/`: Vendored OpenAPI YAML files (inputs to generated API docs).
+- `static/`: Images and other static assets served as-is.
+- `blog/`, `code_samples/`: Blog posts and reusable examples/snippets.
+
+## Build, Test, and Development Commands
+
+- `nvm use`: Use the Node version from `.nvmrc` (CI uses Node 22).
+- `npm ci`: Install dependencies from `package-lock.json`.
+- `npm run start`: Run the local Docusaurus dev server.
+- `npm run build`: Full build (runs `check-vendored-yaml`, generates OpenAPI docs, then builds to `build/`).
+- `npm run gen-api-docs-all`: Generate OpenAPI docs (writes under `docs/OpenAPI-clients/` when present/needed).
+- `npm run check-vendored-yaml`: Verify vendored OpenAPI YAML matches upstream.
+- `npm run update-vendored-yaml`: Refresh vendored specs in `specs/` from upstream.
+
+Docs-only checks:
+- `vale sync`: Install Vale styles configured in `.vale.ini`.
+- `git diff --name-only | xargs vale --glob='!blog/*'`: Lint changed docs (matches CI’s “added lines” behavior closely).
+
+## Coding Style & Naming Conventions
+
+- Indentation: 2 spaces; newlines: LF (see `.editorconfig`).
+- Docs: prefer `.mdx`; name new pages `kebab-case.mdx`, and use `index.mdx` for section landing pages.
+- Keep long examples in `code_samples/` and reference them from docs instead of duplicating.
+
+## Testing Guidelines
+
+- There is no dedicated unit test runner; CI primarily validates `npm run build` and Vale.
+- If you touch `docs/getting-started/` Docker Compose instructions, sanity-check them locally when feasible.
+
+## Commit & Pull Request Guidelines
+
+- Commits follow Conventional Commits as seen in history: `feat(docs): …`, `fix(docs): …`, `chore(deps): …`.
+- PRs should include: a clear summary, linked issue/ticket when applicable, and screenshots for layout/theme changes.
+- Generated content: treat `docs/OpenAPI-clients/` as derived output; prefer updating `specs/` via `npm run update-vendored-yaml`.
+- CODEOWNERS: changes to `package.json` / `package-lock.json` require review from `@opentdf/security` in addition to maintainers.