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)

test/harness.ts

@@ -0,0 +1,42 @@
+import { runCli } from "../src/cli.js";
+
+export interface CliResult {
+  stdout: string;
+  exitCode: number;
+}
+
+export interface CliTestOptions {
+  env?: Record<string, string | undefined>;
+  cwd?: string;
+}
+
+/**
+ * Drive the CLI seam: argv in, stdout and exit code out. The environment is
+ * fully explicit — nothing leaks in from the test process's own env.
+ */
+export async function runCliTest(
+  argv: string[],
+  options: CliTestOptions = {},
+): Promise<CliResult> {
+  let stdout = "";
+  const exitCode = await runCli({
+    argv,
+    env: options.env ?? {},
+    cwd: options.cwd ?? process.cwd(),
+    stdout: {
+      write: (chunk: string) => {
+        stdout += chunk;
+      },
+    },
+  });
+  process.exitCode = 0;
+  return { stdout, exitCode };
+}
+
+export function testModeEnv(apiUrl: string): Record<string, string> {
+  return {
+    GITEA_AXI_API_URL: apiUrl,
+    GITEA_AXI_TOKEN: "test-token",
+    GITEA_AXI_REPO: "testowner/testrepo",
+  };
+}