feat(deploy): add self-hosted homelab deploy toolkit

- deploy/deploy.sh: idempotent deploy script with dynamic port
  allocation (3011..30200), flock-based concurrency, atomic
  .postgrest-port/.nextjs-port writes, port cleanup of the previous
  deploy + dev stack, nginx config rendering+reload, healthchecks
  with rollback, optional image pruning
- deploy/docker-compose.yml + Dockerfile.nextjs: example stack
  consuming ${POSTGREST_HOST_PORT} / ${NEXTJS_HOST_PORT} (kept as
  reference; the repo's root docker-compose.yml is the source of
  truth for the actual production stack)
- deploy/nginx.conf.template: /api/* -> PostgREST, /* -> Next.js
- deploy/.env.production.example: managed port block + preserved secrets
- deploy/healthcheck.sh: standalone health probe (cron-friendly)
- deploy/Makefile: deploy/status/health/logs/down/rollback targets
- deploy/GITEA_SETUP.md: webhook vs Actions runner instructions
- deploy/README.md + deploy/.gitignore

Note: .gitea/workflows/deploy.yml was deliberately not added — the
existing workflow at that path on Gitea main is the source of truth
and is left untouched.

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