`readCodemanEnv()` in cli.ts and `parseEnvFile()`/`readCodemanCredentials()` in
tui-client.ts were two copies of the same `.env` reader (the TUI's said so in a
comment), and `codeman agent` was about to need a third. They move into
`src/codeman-credentials.ts`; `codeman attach` and the TUI read from it, and the
TUI keeps re-exporting its names so nothing that imports them changes.
The lookup order is one pure function, `credentialsFrom(env, fileEnv)`: each
field from the environment, then the file, username defaulting to `admin` — the
order attach and the TUI already used. `readCodemanCredentials` takes the
environment as a parameter so a caller with its own (the agent CLI's guard) gets
the same answer. The parser now also tolerates an `export ` prefix, which the
agent skill's preamble already accepted in the same file.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
