Add overview repo and verae-nats-process expansion template

High-level system map with diagrams, TOC, and a docs index. Template
worker shows how to add a new verae.* address for search, storage, or
unplanned functions without teaching Zapier NATS.

packages/verae-nats-process/test/handle.test.js

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+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import { handle } from '../src/handle.js';
+import { SUBJECTS } from '../src/subjects.js';
+
+describe('verae-nats-process template', () => {
+  it('uses the verae.area.resource.action address pattern', () => {
+    assert.equal(SUBJECTS.IN, 'verae.example.process.in');
+    assert.equal(SUBJECTS.OUT, 'verae.example.process.out');
+    assert.match(SUBJECTS.reply('abc'), /^verae\.example\.process\.reply\.abc$/);
+  });
+
+  it('handle requires correlation and is idempotent-shaped', () => {
+    assert.throws(() => handle({}), /correlationId/);
+    const a = handle({ correlationId: 'c1', payload: { q: 1 } });
+    const b = handle({ correlationId: 'c1', payload: { q: 1 } });
+    assert.equal(a.ok, true);
+    assert.equal(a.correlationId, b.correlationId);
+    assert.equal(a.echo.q, 1);
+  });
+});