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/Makefile

@@ -0,0 +1,54 @@
+# =============================================================================
+# Makefile — convenience targets around deploy.sh
+# =============================================================================
+# All targets are wrappers; you can also invoke deploy.sh directly.
+
+SHELL := /usr/bin/env bash
+.SHELLFLAGS := -Eeu -o pipefail -c
+.SHELLFLAGS_LOG := $(.SHELLFLAGS)
+
+DEPLOY     := ./deploy.sh
+HEALTH     := ./healthcheck.sh
+WORKSPACE  ?= $(CURDIR)
+
+.PHONY: help
+help: ## Show this help message
+	@awk 'BEGIN {FS = ":.*##"; printf "Targets:\n"} /^[a-zA-Z_-]+:.*##/ { printf "  %-20s %s\n", $$1, $$2 }' $(MAKEFILE_LIST)
+
+.PHONY: deploy
+deploy: ## Run a full deploy (build + up + nginx + healthcheck)
+	$(DEPLOY)
+
+.PHONY: deploy-verbose
+deploy-verbose: ## Deploy with extra logging (PRUNE_IMAGES=0, longer healthcheck)
+	PRUNE_IMAGES=0 HEALTHCHECK_TIMEOUT=120 $(DEPLOY)
+
+.PHONY: health
+health: ## Run a one-shot health check against the running stack
+	WORKSPACE=$(WORKSPACE) $(HEALTH)
+
+.PHONY: health-nginx
+health-nginx: ## Health check including the nginx-fronted URL
+	WORKSPACE=$(WORKSPACE) $(HEALTH) --nginx
+
+.PHONY: status
+status: ## Show current prod ports and running containers
+	@echo "PostgREST port:  $$(cat .postgrest-port 2>/dev/null || echo none)"
+	@echo "Next.js port:    $$(cat .nextjs-port 2>/dev/null || echo none)"
+	@cd deploy && docker compose -p prod-app ps
+
+.PHONY: logs
+logs: ## Tail deploy.log
+	tail -n 200 -f deploy.log
+
+.PHONY: down
+down: ## Stop the production stack (without redeploying)
+	cd deploy && docker compose -p prod-app down --remove-orphans
+
+.PHONY: rollback
+rollback: ## Restart the previous stack (the one whose ports are still on disk)
+	@if [[ ! -f .postgrest-port ]]; then echo "no .postgrest-port to roll back to"; exit 1; fi
+	cd deploy && \
+	  POSTGREST_HOST_PORT=$$(cat ../.postgrest-port) \
+	  NEXTJS_HOST_PORT=$$(cat ../.nextjs-port) \
+	  docker compose -p prod-app --env-file ../.env.production up -d