feat(cli): extract Obelisk runtime into npm package

Add @obelisk-apps/cli with the existing build, search, query, and attune contract plus official skill installation.

Separate the docs-only skill artifact, bootstrap installer, release layout, cross-platform CI, and package-level regression coverage.

tests/cli-test-helpers.mjs

@@ -0,0 +1,18 @@
+import { spawnSync } from 'node:child_process';
+import { dirname, join, resolve } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+export const repoRoot = resolve(dirname(fileURLToPath(import.meta.url)), '..');
+export const cliEntry = join(repoRoot, 'packages', 'cli', 'dist', 'cli', 'src', 'obelisk.js');
+
+export function runCli(args, { home, env = {}, cwd = repoRoot } = {}) {
+  return spawnSync(process.execPath, [cliEntry, ...args], {
+    cwd,
+    env: {
+      ...process.env,
+      ...(home ? { HOME: home, USERPROFILE: home } : {}),
+      ...env,
+    },
+    encoding: 'utf8',
+  });
+}