feat(17-02): add gocron dependency, subscribers and scheduled_jobs tables with CRUD

- Add gocron/v2 v2.19.1 as direct dependency
- Append subscribers and scheduled_jobs CREATE TABLE to schema.sql
- Implement full subscriber CRUD (Add/Remove/List/IsSubscribed)
- Implement full scheduled job CRUD (Save/List/Get/Delete/UpdateLastRun/SetEnabled)

pkg/storage/schema.sql

@@ -55,3 +55,23 @@ CREATE TABLE IF NOT EXISTS custom_dorks (
 
 CREATE INDEX IF NOT EXISTS idx_custom_dorks_source ON custom_dorks(source);
 CREATE INDEX IF NOT EXISTS idx_custom_dorks_category ON custom_dorks(category);
+
+-- Phase 17: Telegram bot subscribers for auto-notifications.
+CREATE TABLE IF NOT EXISTS subscribers (
+    chat_id INTEGER PRIMARY KEY,
+    username TEXT,
+    subscribed_at DATETIME DEFAULT CURRENT_TIMESTAMP
+);
+
+-- Phase 17: Cron-based scheduled scan jobs.
+CREATE TABLE IF NOT EXISTS scheduled_jobs (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    name TEXT UNIQUE NOT NULL,
+    cron_expr TEXT NOT NULL,
+    scan_command TEXT NOT NULL,
+    notify_telegram BOOLEAN DEFAULT FALSE,
+    enabled BOOLEAN DEFAULT TRUE,
+    last_run DATETIME,
+    next_run DATETIME,
+    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
+);