Introduce the first mutations, along with the shared machinery the later
issue and PR mutation slices reuse.
- `issue create` with --title/--body/--body-file/--assignee/--label/
--milestone/--fields, emitting `issue: { number, title, state, url }`
- `issue comment <n>`, echoing the created comment from the POST response
with the body cleaned and truncated at 800 chars
- body-source resolution (--body vs --body-file), label and milestone
name->ID lookup, repeatable flags, and the `joined`/`selectExtraFields`
field extractors
Label lookup pages until exhausted, since a repo with more labels than one
page would otherwise fail to resolve a valid name. The end-to-end tier seeds
a mixed-case label and milestone and passes both in a different case, so the
case-insensitive lookup is verified against live Gitea rather than only
against fixtures.
Add the end-to-end test tier: a Gitea Actions workflow (GitHub-compatible)
that runs the unit+integration tiers plus e2e tests against a pinned
disposable Gitea service container. The e2e suite provisions its own repo,
token, and seed data over HTTP and drives the real CLI seam, gated on
GITEA_AXI_E2E_URL so the default suite stays dependency-free.
A fixture-vs-live shape guard anchors the issue-list FieldDef paths against
both the recorded fixture and the live response, failing on divergence.
