Merge PR #48: feat: add Xiaohongshu source + Reddit public fallback

- Xiaohongshu search via local MCP service (opt-in, zero impact if service not running)
- Reddit public JSON fallback (works with zero API keys)
- Reddit priority: ScrapeCreators -> OpenAI -> public fallback
- Updated env.py: Reddit always available via public fallback

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

vendor/package/dist/lib/normalize-handle.js

@@ -0,0 +1,31 @@
+const HANDLE_REGEX = /^[A-Za-z0-9_]{1,15}$/;
+export function normalizeHandle(input) {
+    const raw = (input ?? '').trim();
+    if (!raw) {
+        return null;
+    }
+    const withoutAt = raw.startsWith('@') ? raw.slice(1) : raw;
+    const handle = withoutAt.trim();
+    if (!handle) {
+        return null;
+    }
+    // X/Twitter handles are traditionally max 15 chars; keep strict to avoid surprising queries.
+    if (!HANDLE_REGEX.test(handle)) {
+        return null;
+    }
+    return handle;
+}
+export function mentionsQueryFromUserOption(userOption) {
+    if (typeof userOption === 'undefined') {
+        return { query: null, error: null };
+    }
+    const handle = normalizeHandle(userOption);
+    if (!handle) {
+        return {
+            query: null,
+            error: 'Invalid --user handle. Expected something like @steipete (letters, digits, underscore; max 15).',
+        };
+    }
+    return { query: `@${handle}`, error: null };
+}
+//# sourceMappingURL=normalize-handle.js.map