refactor(e2e): extract infrastructure into tests/e2e/infra/ module

- Move fixtures.ts, llm-judge.ts, results-db.ts to tests/e2e/infra/
- Deduplicate wdio.conf.js: use createTestFixture() instead of inline copy
- Replace __dirname paths with projectRoot-anchored paths
- Create test-mode-constants.ts (typed env var names, flag registry)
- Create scripts/preflight-check.sh (validates tauri-driver, display, Claude CLI)
- Create scripts/check-test-flags.sh (CI lint for AGOR_TEST flag drift)
- Rewrite tests/e2e/README.md with full documentation
- Update spec imports for moved infra files

scripts/preflight-check.sh

@@ -0,0 +1,68 @@
+#!/usr/bin/env bash
+# Preflight check for E2E tests — validates system dependencies.
+# Run before E2E suite to catch missing tools early.
+
+set -euo pipefail
+
+OK=0
+WARN=0
+
+check() {
+  local name="$1" cmd="$2"
+  if eval "$cmd" >/dev/null 2>&1; then
+    echo "  ✓ $name"
+  else
+    echo "  ✗ $name"
+    return 1
+  fi
+}
+
+echo "E2E Preflight Check"
+echo "==================="
+
+echo ""
+echo "Required:"
+
+if ! check "tauri-driver" "command -v tauri-driver"; then
+  echo "    Install: cargo install tauri-driver"
+  OK=1
+fi
+
+if ! check "debug binary" "test -f target/debug/agent-orchestrator"; then
+  echo "    Build: cargo tauri build --debug --no-bundle"
+  OK=1
+fi
+
+# Display server (Linux only)
+if [[ "$(uname)" == "Linux" ]]; then
+  if [[ -n "${DISPLAY:-}" ]] || [[ -n "${WAYLAND_DISPLAY:-}" ]]; then
+    echo "  ✓ display server (DISPLAY=$DISPLAY)"
+  else
+    echo "  ✗ display server — no DISPLAY or WAYLAND_DISPLAY set"
+    echo "    Use: xvfb-run --auto-servernum npm run test:e2e"
+    OK=1
+  fi
+fi
+
+echo ""
+echo "Optional (LLM judge):"
+
+if command -v claude >/dev/null 2>&1; then
+  echo "  ✓ Claude CLI ($(which claude))"
+elif [[ -n "${ANTHROPIC_API_KEY:-}" ]]; then
+  echo "  ✓ ANTHROPIC_API_KEY set"
+else
+  echo "  ~ Claude CLI not found, ANTHROPIC_API_KEY not set"
+  echo "    LLM-judged tests will be skipped"
+  WARN=1
+fi
+
+echo ""
+if [[ $OK -ne 0 ]]; then
+  echo "FAILED — missing required dependencies"
+  exit 1
+elif [[ $WARN -ne 0 ]]; then
+  echo "PASSED with warnings"
+else
+  echo "ALL CHECKS PASSED"
+fi