feat: add e2e test suite with Robot Framework

Add e2e/ dir with Robot Framework tests for page loading, ban records,
blocklist import, config edit. Add requirements.txt. Update Makefile with
test commands. Update .gitignore, backend docs, testing requirements docs.

Makefile

@@ -12,6 +12,7 @@
 #    make logs         — tail logs for all debug services
 #    make restart      — restart the debug stack
 #    make dev-ban-test — one-command smoke test of the ban pipeline
+#    make e2e          — run the Robot Framework E2E test suite
 # ──────────────────────────────────────────────────────────────
 
 COMPOSE_FILE := Docker/compose.debug.yml
@@ -39,7 +40,7 @@ COMPOSE := $(shell command -v podman-compose 2>/dev/null \
 # Detect available container runtime (podman or docker).
 RUNTIME := $(shell command -v podman 2>/dev/null || echo "docker")
 
-.PHONY: up down build restart logs clean dev-ban-test
+.PHONY: up down build restart logs clean dev-ban-test e2e
 
 ## Start the debug stack (detached).
 ## Ensures log stub files exist so fail2ban can open them on first start.
@@ -71,6 +72,20 @@ clean:
 	$(RUNTIME) rmi $(DEV_IMAGES) 2>/dev/null || true
 	@echo "All debug volumes and local images removed. Run 'make up' to rebuild and start fresh."
 
+## Run the Robot Framework E2E test suite.
+## Requires: stack up (make up), BANGUI_SESSION_SECRET env var set.
+## Installs: pip install -r e2e/requirements.txt && rfbrowser init
+e2e: up
+	@echo "Waiting for stack to be healthy..."
+	@timeout=120; \
+	until curl -sf http://localhost:8000/api/health > /dev/null 2>&1; do \
+	  sleep 5; timeout=$$((timeout-5)); \
+	  if [ $$timeout -le 0 ]; then echo "Backend not healthy after 120s"; exit 1; fi; \
+	done
+	pip install -r e2e/requirements.txt -q
+	rfbrowser init --quiet
+	robot --outputdir e2e/results e2e/tests/
+
 ## One-command smoke test for the ban pipeline:
 ##   1. Start fail2ban, 2. write failure lines, 3. check ban status.
 dev-ban-test: