chore(migrations): add migration script for ivanti_counts_history table

Standalone migration script for consistency with other files in
backend/migrations/. The table is also created automatically at server
startup via CREATE TABLE IF NOT EXISTS in initTables() so no manual
step is required on the dev server — just restart the backend after
pulling.

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

backend/migrations/add_ivanti_counts_history_table.js

@@ -0,0 +1,41 @@
+// Migration: Add ivanti_counts_history table
+//
+// Stores a snapshot of open/closed Ivanti finding counts on every sync.
+// Unlike ivanti_counts_cache (single-row, always overwritten), this table
+// accumulates all snapshots so time-series charts can be built from it.
+//
+// The GET /api/ivanti/findings/counts/history endpoint aggregates these rows
+// to the last snapshot per calendar day using a ROW_NUMBER window function.
+//
+// NOTE: This table is also created automatically at server startup via
+// CREATE TABLE IF NOT EXISTS in initTables() (ivantiFindings.js).
+// This script is provided for manual setup on fresh installs and for
+// documentation consistency with other migration files.
+//
+// Usage: node backend/migrations/add_ivanti_counts_history_table.js
+
+const sqlite3 = require('sqlite3').verbose();
+const path    = require('path');
+
+const dbPath = path.join(__dirname, '..', 'cve_database.db');
+const db     = new sqlite3.Database(dbPath);
+
+console.log('Starting ivanti_counts_history migration...');
+
+db.serialize(() => {
+    db.run(`
+        CREATE TABLE IF NOT EXISTS ivanti_counts_history (
+            id           INTEGER PRIMARY KEY AUTOINCREMENT,
+            open_count   INTEGER NOT NULL,
+            closed_count INTEGER NOT NULL,
+            recorded_at  DATETIME DEFAULT CURRENT_TIMESTAMP
+        )
+    `, (err) => {
+        if (err) console.error('Error creating ivanti_counts_history table:', err);
+        else console.log('✓ ivanti_counts_history table created (or already exists)');
+    });
+});
+
+db.close(() => {
+    console.log('Migration complete.');
+});