Refactor code structure and update versioning for AI Assistant

[ric-v]

This pull request updates documentation and marketplace assets to reflect new features, improved branding, and the latest release status for the PgStudio extension. It reorganizes and expands the GIF/demo sections in the documentation, updates security support information, and improves metadata and layout for marketplace and overview pages.

Documentation and Asset Updates:

• Expanded and reorganized demo GIFs in README.md and MARKETPLACE.md, introducing new sections for features like Dashboard, DB Operations, Power Editor, and More Features. Updated existing sections for clarity and renamed some features for consistency. [1] [2]
• Updated GIF references and alt text in docs/html/editor-file-views.html to match new naming and feature structure. Added new GIF demo articles for Dashboard, DB Operations, Power Editor, and More Features. [1] [2] [3] [4]
• Changed the main screenshot and improved meta tags for SEO and marketplace display in both docs/html/editor-file-views.html and docs/html/minimized-overview.html. [1] [2]

Branding and Layout Improvements:

• Added the NexQL logo and improved the layout of the minimized overview section, including better formatting of feature pills and descriptions for clarity and accessibility. [1] [2]

Security and Release Status:

• Updated SECURITY.md to indicate active support for version 1.0.x and dropped support for pre-1.0.0 versions.

Housekeeping:

• Removed the now-outdated FIXES_APPLIED.md file, as recent critical TypeScript fixes are now merged and reflected in the current release.