fix(test): expect provider empty durable input

[tkkhq]

Tracking

• Related: https://github.com/Kong/volcano-hosting/actions/runs/35433219976
• Related: https://github.com/Kong/volcano-hosting/pull/1174

Why

• the cloud E2E test expected a missing durable input as null, while the provider passes the empty input object as the serialized value "{}"

Summary

• update the durable start assertion to match the provider input envelope

Verification

• gofmt -d tests/e2e/api/durable_functions_test.go
• go test ./tests/e2e/api -run '^$'
• git diff --check origin/main...HEAD

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[swkeever]

No actionable findings. The fixture echoes the raw InputPayload string, and the linked staging failure shows exactly the newly expected "echoed": "{}". Existing unit tests still verify that an omitted CLI input sends no request body. Verified: unit tests for internal/api, internal/cmd/durable, and internal/output; E2E package compilation; gofmt; and diff whitespace checks. The full cloud E2E was not rerun locally.

[marckong]

Reviewed the full diff and traced the no-input path through the CLI request, hosting handoff, and Lambda durable envelope. The assertion matches the observed provider contract while existing unit coverage continues to verify that the CLI sends an empty request body. No actionable findings; local tests/lint and required CI checks pass.