fix(mindspace): lower page access password minimum to 6 characters

Align publication validation, portal gate HTML, H5 publish UI, MCP docs,
and page-data skill guidance so passwords like 888888 are accepted while
3-character values such as 888 remain rejected.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/components/MindSpacePageDataOpsPanel.tsx

@@ -401,12 +401,12 @@ export function MindSpacePageDataOpsPanel({ pageId, pageTitle, accessMode, onClo
                   type="password"
                   value={newPassword}
                   onChange={(event) => setNewPassword(event.target.value)}
-                  placeholder="新页面口令（至少 8 位）"
+                  placeholder="新页面口令（至少 6 位）"
                   autoComplete="new-password"
                 />
                 <button
                   type="button"
-                  disabled={busyAction != null || newPassword.trim().length < 8}
+                  disabled={busyAction != null || newPassword.trim().length < 6}
                   onClick={() =>
                     void runAction('reset-password', async () => {
                       const result = await resetPageDataPassword(pageId, newPassword.trim());

src/components/MindSpacePageDetail.tsx

@@ -1362,7 +1362,7 @@ export function MindSpacePageDetail({
               <input
                 type="password"
                 value={accessPassword}
-                minLength={8}
+                minLength={6}
                 maxLength={128}
                 autoComplete="new-password"
                 onChange={(event) => {