`pr review <n>` gains `--comments-file <path>`, a JSON array of inline
comments submitted with the review. Each entry is one of two exclusive
shapes: a new comment `{ path, line, body }` (mapped to `new_position`,
always the new side) or a reply `{ reply_to, body }`. A reply carries no
line or side — gitea-axi finds the target via the reviews-plus-comments
fan-out (there is no get-comment-by-id endpoint), reconstructs its anchor
from the target's own `diff_hunk`, and infers old/new side from it, so a
same-line post threads with the existing conversation. All entries map
onto the review-submission payload's `comments[]`; no new HTTP layer is
added. An unknown `reply_to` is a VALIDATION_ERROR raised before the POST,
and the submitted inline-comment count rides the action block.
The shared path-resolve-and-read behind --body-file and --comments-file is
extracted into src/flag-file.ts.
Add `pr review <n>` with the three action switches --approve,
--request-changes, and --comment, plus --body/--body-file. Exactly one
action flag is required; zero or multiple raise VALIDATION_ERROR before
any API call, mirroring the merge shorthand-conflict rule. Body
requirements are left to Gitea: a body-less event it rejects surfaces its
422 as VALIDATION_ERROR carrying the server's message. Output is
`review: { number, action }`.
