release: 1.0.0, a changelog, one .env.example and the docs to match

- CHANGELOG.md and CHANGELOG.pt-BR.md, from the project history.
- .env.example now serves development and production; scripts/init-env.sh
  (make env) creates .env with random secrets. .env.production.example is gone.
- docs/RELEASING.md: the pipeline, how a version is cut and deployed, the runners.
- DEPLOYMENT.md and both READMEs updated for Gitea and the new env flow.
- Service versions set to 1.0.0.
- CI: the proxy network step is idempotent and the stack is torn down always,
  since the runner's Docker daemon now outlives a job.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

services/webmail/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@lambdamail/webmail",
-  "version": "0.1.0",
+  "version": "1.0.0",
   "private": true,
   "scripts": {
     "dev": "next dev",