fix(hooks): extract doc-warning hook to external script to fix CI

The inline JS in the Write PreToolUse hook had a multi-layer escaping
bug: the regex [\\/\\] collapsed to [\/\] after the validator's
unescape chain, producing an invalid regex (Unmatched ')').

Fix: move the doc-file-warning hook to scripts/hooks/pre-write-doc-warn.js,
eliminating the inline escaping problem entirely. All 992 tests now pass.

Closes the 991/992 CI failure on main.

scripts/hooks/pre-write-doc-warn.js

@@ -0,0 +1,61 @@
+#!/usr/bin/env node
+/**
+ * PreToolUse Hook: Warn about non-standard documentation files
+ *
+ * Cross-platform (Windows, macOS, Linux)
+ *
+ * Runs before Write tool use. If the file is a .md or .txt file that isn't
+ * a standard documentation file (README, CLAUDE, AGENTS, etc.) or in an
+ * expected directory (docs/, skills/, .claude/plans/), warns the user.
+ *
+ * Exit code 0 — warn only, does not block.
+ */
+
+const path = require('path');
+
+const MAX_STDIN = 1024 * 1024; // 1MB limit
+let data = '';
+process.stdin.setEncoding('utf8');
+
+process.stdin.on('data', chunk => {
+  if (data.length < MAX_STDIN) {
+    const remaining = MAX_STDIN - data.length;
+    data += chunk.length > remaining ? chunk.slice(0, remaining) : chunk;
+  }
+});
+
+process.stdin.on('end', () => {
+  try {
+    const input = JSON.parse(data);
+    const filePath = input.tool_input?.file_path || '';
+
+    // Only check .md and .txt files
+    if (!/\.(md|txt)$/.test(filePath)) {
+      process.stdout.write(data);
+      return;
+    }
+
+    // Allow standard documentation files
+    const basename = path.basename(filePath);
+    if (/^(README|CLAUDE|AGENTS|CONTRIBUTING|CHANGELOG|LICENSE|SKILL)\.md$/i.test(basename)) {
+      process.stdout.write(data);
+      return;
+    }
+
+    // Allow files in .claude/plans/, docs/, and skills/ directories
+    const normalized = filePath.replace(/\\/g, '/');
+    if (/\.claude\/plans\//.test(normalized) || /(^|\/)(docs|skills)\//.test(normalized)) {
+      process.stdout.write(data);
+      return;
+    }
+
+    // Warn about non-standard documentation files
+    console.error('[Hook] WARNING: Non-standard documentation file detected');
+    console.error('[Hook] File: ' + filePath);
+    console.error('[Hook] Consider consolidating into README.md or docs/ directory');
+  } catch {
+    // Parse error — pass through
+  }
+
+  process.stdout.write(data);
+});