Add felhom-hub: multi-customer dashboard service

- Hub service receives reports from customer controllers
- SQLite store with 90-day retention and auto-prune
- REST API: POST /api/v1/report, GET /api/v1/customers
- Dark theme dashboard with status overview table
- Customer detail page with system, storage, containers, backup, health
- Bearer token auth for report ingest, bcrypt auth for dashboard
- K8s manifest for felhom-system namespace (Deployment, Service, Ingress, PVC)
- Dockerfile with multi-stage build

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

hub/Makefile

@@ -0,0 +1,25 @@
+VERSION ?= dev
+BUILD_TIME := $(shell date -u +"%Y-%m-%dT%H:%M:%SZ")
+REGISTRY := gitea.dooplex.hu/admin
+IMAGE := $(REGISTRY)/felhom-hub
+
+.PHONY: build run docker docker-push clean
+
+build:
+	CGO_ENABLED=0 go build -ldflags "-s -w -X main.Version=$(VERSION) -X main.BuildTime=$(BUILD_TIME)" \
+		-o bin/felhom-hub ./cmd/hub/
+
+run: build
+	./bin/felhom-hub -config configs/hub.yaml.example
+
+docker:
+	docker build --build-arg VERSION=$(VERSION) --build-arg BUILD_TIME=$(BUILD_TIME) \
+		-t $(IMAGE):$(VERSION) .
+
+docker-push: docker
+	docker push $(IMAGE):$(VERSION)
+	docker tag $(IMAGE):$(VERSION) $(IMAGE):latest
+	docker push $(IMAGE):latest
+
+clean:
+	rm -rf bin/