feat: complete issue list filters, sort, and fields (task 0002)

Finish the `issue list` flag surface left minimal by the tracer slice:

- Server-side filters `--label`, `--assignee`, `--author`, `--milestone`,
  mapped to Gitea's `labels`, `assigned_by`, `created_by`, `milestones`.
- Client-side `--sort <created|updated|comments>`, always descending, over
  the fully paginated set (ADR 0005); `--limit` caps the sorted result.
- `--fields` exposing body, closedAt, labels, milestone, updatedAt, url.
- `--search` refused with a VALIDATION_ERROR redirecting to `search issues`.

Exhaustive pagination lands as a shared `paginate.ts`, since ADR 0005 makes
it a policy later slices reuse; `lookup.ts` drops its hand-rolled copy of the
same loop. The helper carries the 20-page cap that copy encoded, matching the
1000-item ceiling Principle 8 sets.

.claude/tasks/0002-issue-list-filters-and-fields.md

@@ -13,9 +13,25 @@ Field selection: `--fields <a,b,c>` exposing the extra fields `body` (raw), `clo
 
 ## Acceptance criteria
 
-- [ ] `--label`, `--assignee`, `--author`, and `--milestone` map to their Gitea API query params and filter server-side
-- [ ] `--sort <created|updated|comments>` reorders descending client-side after full pagination; the count line still reports `T` from `X-Total-Count`
-- [ ] `--fields` selects among the documented extra fields, each rendered via its FieldDef extractor (relative times, joined label names, milestone title)
-- [ ] Output contains no `type` field
-- [ ] `--search` fails with `VALIDATION_ERROR` (exit 2) and a help line pointing at `gitea-axi search issues "<query>"`
-- [ ] Fixture-server tests cover each filter, client-side sort with pagination, `--fields` extraction, and the forbidden `--search`
+- [x] `--label`, `--assignee`, `--author`, and `--milestone` map to their Gitea API query params and filter server-side
+- [x] `--sort <created|updated|comments>` reorders descending client-side after full pagination; the count line still reports `T` from `X-Total-Count`
+- [x] `--fields` selects among the documented extra fields, each rendered via its FieldDef extractor (relative times, joined label names, milestone title)
+- [x] Output contains no `type` field
+- [x] `--search` fails with `VALIDATION_ERROR` (exit 2) and a help line pointing at `gitea-axi search issues "<query>"`
+- [x] Fixture-server tests cover each filter, client-side sort with pagination, `--fields` extraction, and the forbidden `--search`
+
+## Implementation Notes
+
+Exhaustive pagination landed as a shared `src/paginate.ts` (`fetchAllPages`, `readTotalCount`), since ADR 0005 makes it a policy that later slices (`pr list`, the dashboard) reuse rather than a detail of this command.
+`lookup.ts`'s `listAllLabels` hand-rolled the same loop and now calls the shared helper, which removed its local `LABEL_PAGE_SIZE`/`LABEL_PAGE_LIMIT` constants.
+The helper carries the 20-page cap those constants encoded, matching the 1000-item ceiling Principle 8 sets on exhaustive pagination — without it a server that ignores paging would loop forever.
+
+Two count-line details the acceptance criteria did not spell out.
+Under `--sort`, `--limit` caps the *sorted* result rather than the fetch, so pages are always read at the full page size of 50 and the top `N` by the sort key is what the limit selects.
+Also under `--sort`, when an instance omits `X-Total-Count`, the total falls back to the size of the fully paginated set instead of degrading to `count: N (showing first N)` — everything was fetched to sort it, so the total is known, and Principle 4 says a total is always reported.
+
+`--sort` and `--state` shared an enum-parsing shape, now extracted as `parseEnumFlag` in `flags.ts`.
+
+**Open question for the spec, deliberately not resolved here:** `--fields body` renders the body raw and untruncated, exactly as this task and the spec's command surface specify ("`body` (raw)"), matching the already-merged `issue create --fields body`.
+This contradicts Principle 3 ("Body text is truncated at **500 characters** in all contexts (list and detail alike)"): a 30-row list with `--fields body` can now emit 30 full bodies, which is the cost Principle 3 exists to prevent.
+Truncating here alone would make `issue list` disagree with `issue create`, so the conflict wants one ruling applied to both commands rather than a silent divergence in this slice.