Make nisse-testing-operator a Gitea operator in the test config only

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE

.env.example

@@ -11,6 +11,9 @@ NISSE_LLM_TOKEN=replace-me
 NISSE_MATRIX_TOKEN=replace-me
 # gitea.token: the Gitea service account's scoped token (B2)
 NISSE_GITEA_TOKEN=replace-me
+# The end-to-end tests' scripted operator (nisse-testing-operator): scopes
+# write:issue and write:repository, write access to the sandbox only.
+NISSE_OPERATOR_TOKEN=replace-me
 # The live push test reads the sandbox's deploy key from the path in
 # tests/integration/nisse-test.yaml (gitea.push_key), not from here.