A controller that started before the forge's host had published its token
ran without forge access until someone restarted it: on a split-host first
deploy that is a manual step. Now the forge client lives in a slot that is
filled once (`Late<T>`, an `Arc<OnceLock<T>>`):
- `forge::enable` tries the store once at start. On failure it logs once and
re-reads in the background with backoff (30s doubling to a 5-minute cap,
no log per retry), fills the slot and logs once when the token is there.
- The forge passes (#5014's per-hive token mint among them), the config-PR
poll and the webhook registration start from that moment, through
`start_forge`'s callback.
- Job nodes and HTTP handlers read the slot when they run, so they answer
"no forge" before and work after.
A token replaced in the store after the slot is filled still reaches the
controller with its next restart. The round-1 change that shared
`queue_identity::fetch_with_retry` is reverted; nothing else uses it.
Refs #4998
get_issue_report mapped every error from Client::issue_report to 503
(StatusUnavailable) unconditionally. issue_report calls
issue_list_issues(org, repo, ...) first, and a Forgejo 404 there — a
typo'd or deleted repo — was flattened into the same 503 a genuine
forge outage produces, which tells a client to retry a request that
will never succeed.
Downcast the anyhow error back to forgejo_api::ForgejoError (same
pattern main.rs's wanted_error_status uses for
swarm_queue_client::Error) and check it structurally against the
ApiErrorKind::NotFound / UnexpectedStatusCode(404) shapes forgejo's
generated client produces for a 404, rather than string-matching the
rendered message. Only that case answers 404, naming the org/repo;
every other forge failure still answers 503. Updates the route's
OpenAPI response list to document the 404.
Closes#4701
