feat(page-data): complete Phase 4-5, ops UI, and publish integration

Add visitor roles, row-level scope, owner ops APIs, MySQL policy index,
Turnstile captcha, browser client SDK, publish-panel dataset binding,
acceptance tests, and usage documentation.

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

db.mjs

@@ -834,6 +834,19 @@ export async function migrateSchema(pool) {
        AND c.category_code IN ('public', 'oa')`,
   );
 
+  await pool.query(`
+    CREATE TABLE IF NOT EXISTS h5_page_data_policy_index (
+      page_id CHAR(36) PRIMARY KEY,
+      owner_user_id CHAR(36) NOT NULL,
+      access_mode VARCHAR(32) NOT NULL,
+      dataset_count INT UNSIGNED NOT NULL DEFAULT 0,
+      scope_hash CHAR(16) NOT NULL,
+      updated_at BIGINT NOT NULL,
+      KEY idx_h5_page_data_policy_owner (owner_user_id, updated_at),
+      CONSTRAINT fk_h5_page_data_policy_owner FOREIGN KEY (owner_user_id) REFERENCES h5_users(id) ON DELETE CASCADE
+    ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
+  `);
+
   await pool.query(`
     CREATE TABLE IF NOT EXISTS h5_user_feedback (
       id CHAR(36) PRIMARY KEY,