feat: add script field to ScheduledTask type and database layer

Adds optional `script` field to the ScheduledTask interface, with a
migration for existing DBs and full support in createTask/updateTask.

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

src/db.ts

@@ -93,6 +93,15 @@ function createSchema(database: Database.Database): void {
     /* column already exists */
   }
 
+  // Add script column if it doesn't exist (migration for existing DBs)
+  try {
+    database.exec(
+      `ALTER TABLE scheduled_tasks ADD COLUMN script TEXT`,
+    );
+  } catch {
+    /* column already exists */
+  }
+
   // Add is_bot_message column if it doesn't exist (migration for existing DBs)
   try {
     database.exec(
@@ -368,14 +377,15 @@ export function createTask(
 ): void {
   db.prepare(
     `
-    INSERT INTO scheduled_tasks (id, group_folder, chat_jid, prompt, schedule_type, schedule_value, context_mode, next_run, status, created_at)
-    VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+    INSERT INTO scheduled_tasks (id, group_folder, chat_jid, prompt, script, schedule_type, schedule_value, context_mode, next_run, status, created_at)
+    VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
   `,
   ).run(
     task.id,
     task.group_folder,
     task.chat_jid,
     task.prompt,
+    task.script || null,
     task.schedule_type,
     task.schedule_value,
     task.context_mode || 'isolated',
@@ -410,7 +420,7 @@ export function updateTask(
   updates: Partial<
     Pick<
       ScheduledTask,
-      'prompt' | 'schedule_type' | 'schedule_value' | 'next_run' | 'status'
+      'prompt' | 'script' | 'schedule_type' | 'schedule_value' | 'next_run' | 'status'
     >
   >,
 ): void {
@@ -421,6 +431,10 @@ export function updateTask(
     fields.push('prompt = ?');
     values.push(updates.prompt);
   }
+  if (updates.script !== undefined) {
+    fields.push('script = ?');
+    values.push(updates.script || null);
+  }
   if (updates.schedule_type !== undefined) {
     fields.push('schedule_type = ?');
     values.push(updates.schedule_type);

src/types.ts

@@ -58,6 +58,7 @@ export interface ScheduledTask {
   group_folder: string;
   chat_jid: string;
   prompt: string;
+  script?: string | null;
   schedule_type: 'cron' | 'interval' | 'once';
   schedule_value: string;
   context_mode: 'group' | 'isolated';