ci(gitea): add deploy workflow + self-hosted homelab deploy toolkit (Auth.js port)

Ports the deploy pipeline from the Gitea main fork (commit 7ddb06d's deploy
toolkit) into the Auth.js v5 / NextAuth tree:

- .gitea/workflows/deploy.yml: inline deploy that brings up the Docker
  stack, applies migrations, builds Next.js, and runs the app under PM2.
  Swapped Better Auth env vars (BETTER_AUTH_SECRET/URL, NEXT_PUBLIC_BETTER_AUTH_URL)
  for Auth.js v5 names (AUTH_SECRET/URL, NEXT_PUBLIC_AUTH_URL). Dropped
  NEXT_PUBLIC_SUPABASE_URL/ANON_KEY (Supabase removal in progress). Added
  GOOGLE_CLIENT_ID/SECRET + ALLOW_DEV_LOGIN for the Auth.js Google provider
  and dev credentials path. Switched runs-on from 'ubuntu-latest' to the
  self-hosted runner labels matching build.yml.

- deploy/: idempotent deploy toolkit (deploy.sh, docker-compose.yml,
  Dockerfile.nextjs, nginx.conf.template, .env.production.example, healthcheck.sh,
  Makefile, deploy/.gitignore). No auth/Supabase dependencies — pure infra.

- deploy/.env.production.example: renamed NEXTAUTH_SECRET/NEXTAUTH_URL
  (v4) to AUTH_SECRET/AUTH_URL (v5) and added the v5-specific vars
  (NEXT_PUBLIC_AUTH_URL, GOOGLE_*, ALLOW_DEV_LOGIN).

Build pipeline is now end-to-end:
  build.yml → typecheck + lint + build (uses [self-hosted, linux, ubuntu-latest])
  deploy.yml → start docker stack + migrations + build + PM2 restart

Storage / admin code ports (MinIO via @/lib/storage, Supabase removal,
admin-permissions rewrite) are tracked separately — they require porting
the storage and admin code first; the deploy pipeline itself is ready
to run against the Auth.js world.

deploy/.env.production.example

@@ -0,0 +1,52 @@
+# =============================================================================
+# .env.production — secrets + dynamic ports for the running containers
+# =============================================================================
+#
+# deploy.sh writes the first three lines on every successful deploy.
+# Everything below is YOUR responsibility to populate. deploy.sh preserves
+# unknown lines verbatim across deploys (it only overwrites the lines it
+# knows about), so you can safely commit this file to a private repo or
+# provision it via your secrets manager of choice.
+#
+# In production, this file should be mode 0600 and owned by the deploy user.
+# =============================================================================
+
+# --- managed by deploy.sh (do not edit by hand) -------------------------------
+POSTGREST_HOST_PORT=3011
+NEXTJS_HOST_PORT=3012
+NEXT_PUBLIC_API_URL=http://localhost:3011
+
+# --- PostgREST connection ---------------------------------------------------
+PGRST_DB_URI=postgres://app:secret@db.internal:5432/app_production
+PGRST_DB_ANON_ROLE=anon
+PGRST_DB_SCHEMA=public
+
+# --- Next.js server-side secrets -------------------------------------------
+# Anything not prefixed NEXT_PUBLIC_ is server-only and read at request time.
+DATABASE_URL=postgres://app:secret@db.internal:5432/app_production
+
+# Auth.js v5 (NextAuth). Generate AUTH_SECRET with `npx auth secret` or
+# `openssl rand -base64 32`. AUTH_URL is the public base URL the browser
+# uses to build OAuth callback URLs.
+AUTH_SECRET=change-me-to-a-long-random-string
+AUTH_URL=https://app.example.com
+NEXT_PUBLIC_AUTH_URL=https://app.example.com
+ALLOW_DEV_LOGIN=false
+
+# Google OAuth provider for Auth.js. Set both AUTH_GOOGLE_ID/SECRET and
+# GOOGLE_CLIENT_ID/SECRET (the v5 code reads either name).
+GOOGLE_CLIENT_ID=
+GOOGLE_CLIENT_SECRET=
+AUTH_GOOGLE_ID=
+AUTH_GOOGLE_SECRET=
+
+# --- External services ------------------------------------------------------
+STRIPE_SECRET_KEY=sk_live_replace_me
+STRIPE_PUBLISHABLE_KEY=pk_live_replace_me
+STRIPE_WEBHOOK_SECRET=whsec_replace_me
+
+SMTP_HOST=smtp.example.com
+SMTP_PORT=587
+SMTP_USER=apikey
+SMTP_PASSWORD=replace_me
+SMTP_FROM="My App <noreply@example.com>"