feat(api): implement API key management and authentication enhancements

- Added endpoints for managing API keys, including creation, retrieval, updating, and revocation.
- Introduced a new Auth session endpoint to retrieve current tenant and role information.
- Updated the authentication middleware to support API key-based authentication and track last used timestamps.
- Enhanced documentation to reflect new API key functionalities and usage guidelines.
- Improved logging for demo authentication scenarios.

internal/httpapi/test_helpers.go

@@ -0,0 +1,12 @@
+package httpapi
+
+import "testing"
+
+func mustSetTestAPIKeys(t *testing.T, srv *Server, spec string) {
+	t.Helper()
+	resolver, err := newAPIKeyResolver(spec, srv.store)
+	if err != nil {
+		t.Fatal(err)
+	}
+	srv.keyResolver = resolver
+}