Fix missing README on npm; modernize package documentation; add maintainer docs

[oberstet]

Context

AutobahnJS 26.3.1 was just published with strict-mode fixes for Vite 8 / Rolldown. A full-stack demo (Vue 3.6 + Pinia 3 + Vite 8 + Crossbar.io) with Vitest and Playwright tests now exists. The README should reflect this modernized state.

Problem

The npm package page currently shows:

"This package does not have a README. Add a README to your package so that users know how to get started."

This is because packages/autobahn/package.json has a files field that only includes index.js and /lib, and there is no README.md inside packages/autobahn/. npm publishes from that directory, so the repo root README.md never makes it into the tarball.

Root cause

"files": [
  "index.js",
  "/lib"
]

No README.md in packages/autobahn/, and README.md is not listed in files.

Fix

Option A (simplest): Add "README.md" to the files array and either symlink or copy the repo root README into packages/autobahn/.

Option B (better): Create a dedicated packages/autobahn/README.md tailored for npm consumers (install, quick start, link to full docs), since the repo root README contains developer/contributor info that isn't relevant to npm users.

I'd recommend Option B — the npm README should be focused and concise:

1. One-liner: what it is (WAMP for browsers and Node.js)
2. Install: npm install autobahn
3. Quick start example (connect, subscribe, call — 20 lines)
4. Key features (RPC, PubSub, cryptosign auth, browser + Node.js)
5. Compatibility: Node.js 22+, modern browsers, Vite 8 / Rolldown
6. Links: full docs, GitHub repo, Crossbar.io, WAMP spec
7. License

Additional README improvements

The repo root & npm README should contain direct links to the release version on both:

• the Git tagged version on GitHub, e.g. v26.3.1
• the corresponding npm published version, e.g. v26.3.1

The repo root README.md could also use updates:

• Remove outdated references (autobahn-browser, autobahn-xbr, XBR Network links) — XBR is no longer actively developed
• Add Vite 8 / Rolldown bundling guidance (the stub plugin for msgpack5/cbor/when, global: 'globalThis', use_es6_promises: true)
• Add WAMP-cryptosign browser example (using tweetnacl)
• Reference the full-stack demo: blueprints/vue-autobahnjs
• Update the "Platform Requirements" to mention Vite/Rolldown compatibility
• Update code examples to use ES module imports (import autobahn from 'autobahn') alongside the existing CommonJS example

[oberstet]

for maintainers, we should add some basic docs.

e.g. I tend to forget shit not living in JS land most of the time.

stuff such as publish to npm requires:

npm whoami
npm login
just publish-autobahn confirm