v1.0.3 — Email fix, checkbox fix, GitHub auto-updater

Fixes

• Emails not sending — str_contains() replaced with strpos() for PHP 7.x compatibility.
• Checkboxes not persisting — ideabot_field_chk() now echoes correctly. All checkboxes (Bot Enabled, Auto-Open, Hide on Mobile, Enable Webhook) save and display properly.
• Plugin header version — Version tag in plugin header now correctly reads 1.0.3.
• Auto-updater — Reads installed version from WordPress plugin header instead of hardcoded constant.

New

• GitHub auto-updater — WordPress detects new releases from this repo and shows the standard "Update available" notice in the Plugins screen.