readme: quick start, generated capability table, recipes, bridge contract, migration

The readme is rewritten for 2.0: what the library needs, install, the lamp
as quick start, concepts, the table of interfaces, recipes, the bridge
contract, errors, testing without Alexa, migration from 1.x and limits.
scripts/capability-table.js (npm run docs) writes the table from the
registry and the text of three example files into their code blocks;
"Through Alexa" names only the runs of 2026-09-28, made with 1.5.2.
test/readme.test.js fails on a stale table or file, runs
examples/testing/lamp.test.js (MemoryPublisher, no broker) and compiles the
other code blocks. package.json: description, keywords, CHANGELOG.md in files.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

package.json

@@ -1,7 +1,7 @@
 {
   "name": "alex2node",
   "version": "1.5.2",
-  "description": "A Node.js library for creating Alexa-compatible devices using MQTT, based on Alex2MQTT.",
+  "description": "Alexa smart home devices in Node.js over MQTT, through the Alex2MQTT service: declare a device, answer its directives, report its state.",
   "type": "commonjs",
   "main": "./dist/cjs/index.js",
   "module": "./dist/esm/index.js",
@@ -26,6 +26,7 @@
   "scripts": {
     "build": "node scripts/build.mjs",
     "check": "tsc --noEmit && tsc -p test/fixtures/tsconfig.json",
+    "docs": "node scripts/capability-table.js",
     "prepare": "npm run build",
     "test": "node --test test/*.test.js test/*.test.mjs test/*/*.test.js"
   },
@@ -36,6 +37,7 @@
     "iot",
     "home-automation",
     "amazon-alexa",
+    "alexa-smart-home",
     "alex2mqtt"
   ],
   "author": "user511",
@@ -59,6 +61,7 @@
   },
   "files": [
     "dist",
-    "readme.md"
+    "readme.md",
+    "CHANGELOG.md"
   ]
 }