chore: rewrite READMEs purpose-first and drop the build script for prepack (#12)

Rewrites every README to open with what the project and each package are
for, and lines them up with the orpc README shape: centered title, badge
block (codecov, npm downloads, MIT license, Discord, DeepWiki), package
table, and a License footer. Also removes the redundant `build` script
from the downgrader so `prepack` alone drives publishing, and adds the
MIT LICENSE file the packages already declared.

## Docs

- Root README explains the project and lists both packages with one-line
purposes, replacing a bare "OAS" title over the sponsors list.
- Package READMEs lead with the package name and purpose. Downgrader
mappings use shorter table cells and bullet lists, and document two
behaviors the old text missed: path parameters gain `required: true`,
and empty `required` arrays are dropped.
- Generated sponsors sections are byte-identical. `sync-sponsors` runs
end to end and reports zero changes with the new License section after
it.

## Packaging

- `pnpm pack` on the downgrader still runs unbuild via `prepack`;
nothing in docs or CI referenced `build`.
- LICENSE makes the shields license badge resolve. npm download badges
read "not found" until first publish.
- CodSpeed badge left out: the repo has no benchmarks or CodSpeed
project yet.

## Testing

- ESLint passes on all READMEs.
- README code samples verified: the types example type-checks, the
downgrader example produces the documented output.

Author: dinwwwh

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 MiddleAPI
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -1,4 +1,38 @@
-# OAS
+<h1 align="center">OpenAPI Spec</h1>
+
+<div align="center">
+  <a href="https://codecov.io/gh/middleapi/openapi-spec">
+    <img alt="codecov" src="https://codecov.io/gh/middleapi/openapi-spec/branch/main/graph/badge.svg">
+  </a>
+  <a href="https://www.npmjs.com/package/@openapi-spec/types">
+    <img alt="weekly downloads" src="https://img.shields.io/npm/dw/%40openapi-spec%2Ftypes?logo=npm" />
+  </a>
+  <a href="https://github.com/middleapi/openapi-spec/blob/main/LICENSE">
+    <img alt="MIT License" src="https://img.shields.io/github/license/middleapi/openapi-spec?logo=open-source-initiative" />
+  </a>
+  <a href="https://discord.gg/TXEbwRBvQn">
+    <img alt="Discord" src="https://img.shields.io/discord/1308966753044398161?color=7389D8&label&logo=discord&logoColor=ffffff" />
+  </a>
+  <a href="https://deepwiki.com/middleapi/openapi-spec">
+    <img src="https://deepwiki.com/badge.svg" alt="Ask DeepWiki">
+  </a>
+</div>
+
+TypeScript tooling for the [OpenAPI Specification](https://spec.openapis.org/), maintained by [middleapi](https://github.com/middleapi). It lets you work with OpenAPI 3.0, 3.1, and 3.2 documents from one place: precise types for each version, and converters that move a document from a newer version to an older one without losing anything the older version can still express.
+
+| Package                                                                                                         | Description                                                                                         |
+| --------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------- |
+| [`@openapi-spec/types`](https://github.com/middleapi/openapi-spec/blob/main/packages/types/README.md)           | TypeScript types for OpenAPI 3.0, 3.1, and 3.2, with the specification text as JSDoc on every field |
+| [`@openapi-spec/downgrader`](https://github.com/middleapi/openapi-spec/blob/main/packages/downgrader/README.md) | Downgrade documents and Schema Objects one minor version at a time: 3.2 to 3.1 and 3.1 to 3.0       |
+
+## Development
+
+```bash
+pnpm install
+pnpm test
+pnpm lint
+pnpm type:check
+```
 
 ## Sponsors
 
@@ -83,3 +117,7 @@ Like what we build over at [middleapi](https://github.com/middleapi)? You can he
 </table>
 
 With thanks to [36 past sponsors](https://htmlpreview.github.io/?https://github.com/middleapi/static/blob/main/sponsors.svg) who helped get openapi-spec here.
+
+## License
+
+Distributed under the MIT License. See [LICENSE](https://github.com/middleapi/openapi-spec/blob/main/LICENSE) for more information.