docs: migrate README.md / README_ZH.md to a single NRG template

[andriishin]

Why

README.md (EN) and README_ZH.md (Chinese) are hand-maintained side-by-side. Both files are ~1180 lines of curated lists with hundreds of entries — every new addition means editing the same paragraph in two places, and drift between the two is easy to introduce.

This PR migrates both files to a single source-of-truth template using Nanolaba Readme Generator (NRG). Combined with the bundled GitHub Action nanolaba/nrg-action@v1, regeneration happens in CI on every push to master — no toolchain needed locally, just YAML.

What changes

• New: README.src.md — the unified source (~2360 lines). Each line is tagged <!--en--> or <!--zh--> so it appears only in that language's output. The template was generated programmatically by appending each line of README.<lang>.md with its language marker and concatenating the streams. Both regenerated outputs are byte-identical to today's files (modulo a 2-line auto-generated header).
• New: .github/workflows/nrg.yml — runs nanolaba/nrg-action@v1 (pinned to NRG 1.1):
  • Push to master touching README.src.md or the workflow: regenerates and auto-commits any changed READMEs.
  • PR touching any of the three files: drift check in mode: check — fails with a unified diff if a contributor edited a generated file directly.
• Modified: README.md (+2 lines), README_ZH.md (+2 lines) — regenerated. The only change is the 2-line auto-generated header at the top.

The non-default Chinese filename README_ZH.md (rather than the default README.zh.md) is preserved through <!--@nrg.fileNamePattern.zh=README_ZH.md-->.

Verification

Locally, regenerating with NRG 1.1 from Maven Central against current master (commit beb0028) produces output that diffs against the originals only by the 2-line auto-generated header. Zero functional content change. Tested with the same nanolaba/nrg-action@v1 setup that the workflow uses (Java 17 + NRG 1.1).

What's intentionally NOT in this PR

• Translation alignment. The auto-generated template uses per-line language markers — today's content lives unchanged in README.src.md. Future PRs can extract shared structural elements (badge URLs, table headers, anchor labels) into shared regions of the template — incremental, reviewable changes.
• Awesome-list link curation. Nothing in this PR adds, removes, or reorders any list entry. Only the README files and a docs workflow.

How to regenerate locally

curl -L -o nrg.jar https://repo1.maven.org/maven2/com/nanolaba/readme-generator/1.1/readme-generator-1.1.jar
java -jar nrg.jar -f README.src.md

About NRG

com.nanolaba:readme-generator — open-source, Apache 2.0, Java 8+. Ships as a CLI, Maven plugin, GitHub Action, and library. The action approach used here requires zero local toolchain — Java is provisioned by the action.

[agmmnn]

i’ve actually been thinking about doing something like this for a while

looks like the right direction for the repo. i’m a bit busy right now but i’ll take a closer look soon. thanks @andriishin 🙌