feat: scaffold CLI and minimal issue list (task 0001)

Tracer bullet for gitea-axi: runnable npm package on axi-sdk-js with
gitea-js as the sole HTTP layer, ESM on Node 20+.

- issue list with --state/--limit, default fields, count line from
  X-Total-Count, type=issues guard, explicit empty state, and next-step
  suggestions
- repo context detection from the git origin remote (SSH/scp/HTTPS),
  tea credential discovery with the three-way login-matching split, and
  -R/--repo and --login overrides (flag > env > auto)
- token retrieval via tea login helper get: tea's login list JSON
  carries no token (ADR 0001 amended)
- full AxiError classification table with path-based 404 split, TOON
  errors on stdout, exit codes 0/1/2
- test mode (GITEA_AXI_API_URL/TOKEN/REPO) suppressing subprocesses,
  fixture server, and vitest suites driving the CLI seam (50 tests)

src/fields.ts

@@ -0,0 +1,54 @@
+import { relativeTime } from "./time.js";
+
+export interface ExtractContext {
+  now: Date;
+}
+
+export interface FieldDef<T> {
+  name: string;
+  extract: (raw: T, context: ExtractContext) => unknown;
+}
+
+function pluckPath(raw: unknown, path: string): unknown {
+  let value: unknown = raw;
+  for (const key of path.split(".")) {
+    if (typeof value !== "object" || value === null) {
+      return undefined;
+    }
+    value = (value as Record<string, unknown>)[key];
+  }
+  return value;
+}
+
+export function pluck<T>(name: string, path: string = name): FieldDef<T> {
+  return { name, extract: (raw) => pluckPath(raw, path) ?? "" };
+}
+
+export function lowercased<T>(name: string, path: string = name): FieldDef<T> {
+  return {
+    name,
+    extract: (raw) => String(pluckPath(raw, path) ?? "").toLowerCase(),
+  };
+}
+
+export function relativeTimeField<T>(name: string, path: string): FieldDef<T> {
+  return {
+    name,
+    extract: (raw, context) => {
+      const value = pluckPath(raw, path);
+      return relativeTime(typeof value === "string" ? value : undefined, context.now);
+    },
+  };
+}
+
+export function extractRow<T>(
+  raw: T,
+  fields: FieldDef<T>[],
+  context: ExtractContext,
+): Record<string, unknown> {
+  const row: Record<string, unknown> = {};
+  for (const field of fields) {
+    row[field.name] = field.extract(raw, context);
+  }
+  return row;
+}