## Why
After #22 moved the branch-readiness poll before `.version` write, the workflow started failing **every run** with `exitcode '23'` and no error output. Exit 23 = `CURLE_WRITE_ERROR` from curl in the wait loop's `BRANCH_STATUS=$(curl ...)`. With `set -e`, any non-zero status from a command substitution aborts the script before the retry/echo path runs — so the failure was both deterministic and silent.
## Changes
- Introduce an `api_call` helper that wraps curl with `|| rc=$?` and emits `<http_code>|<curl_rc>` plus the response body. Curl exit codes can no longer kill the script via `set -e`.
- Create the `next-release` branch explicitly via `POST /branches` instead of relying on the `new_branch` parameter of the CHANGELOG.md PUT. Eliminates the race between branch creation and subsequent file writes.
- Poll branch readiness after explicit creation.
- Fetch file blob SHAs from `next-release` directly (not base), so writes always carry the correct SHA.
- Every API call (branch create, CHANGELOG.md, .version, PR) now retries 5× with HTTP code, curl exit code, and response body logged on failure.
## Test plan
- [ ] Trigger Release.yml on a repo with a pending changelog entry; confirm branch is created, both files written, and PR opened.
- [ ] On transient errors, log shows HTTP code + curl rc + body on each retry.
Reviewed-on: #23
argoyle
51b3b980a3