fix: use cross-platform Node script for postinstall symlinks (#577)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

scripts/link-aliases.mjs

@@ -0,0 +1,37 @@
+/**
+ * Creates symlink aliases so that AI coding tools other than Claude Code
+ * (e.g., OpenCode, Cursor) can discover project instructions.
+ *
+ * Aliases created:
+ *   .opencode  → .claude       (directory)
+ *   agents     → .claude       (directory)
+ *   AGENTS.md  → CLAUDE.md     (file)
+ *
+ * Cross-platform notes:
+ * - Directory symlinks use 'junction' type, which works on Windows without
+ *   elevated privileges or Developer Mode.
+ * - File symlinks ('file' type) require elevated privileges or Developer Mode
+ *   on Windows. If creation fails, we log a warning instead of crashing
+ *   `pnpm install`. The alias is optional — the canonical files still work.
+ */
+import { existsSync, symlinkSync } from 'node:fs';
+import { resolve } from 'node:path';
+
+const root = resolve(import.meta.dirname, '..');
+
+const aliases = [
+  { target: '.claude', path: '.opencode', type: 'junction' },
+  { target: '.claude', path: 'agents', type: 'junction' },
+  { target: 'CLAUDE.md', path: 'AGENTS.md', type: 'file' },
+];
+
+for (const alias of aliases) {
+  const fullPath = resolve(root, alias.path);
+  if (existsSync(fullPath)) continue;
+
+  try {
+    symlinkSync(alias.target, fullPath, alias.type);
+  } catch {
+    console.warn(`warning: could not create symlink ${alias.path} → ${alias.target}`);
+  }
+}