Release v2.0.0: AI chat sidebar, inline editing, live preview, polish · wpgaurav/page-blocks-builder

Major refactor bringing the standalone plugin to production parity with the MD theme dropin.

Major Features

AI Chat Sidebar — Multi-turn conversation replaces the inline AI bar. Persistent context, "+ New Chat" button, message history. OpenAI, Anthropic, Gemini supported. Theme CSS variables sent as system prompt context.
Inline Text Editing in Preview — Click any heading, paragraph, link, or list item directly in the preview iframe to edit. Enter commits, Escape cancels.
Live Preview Patching — No more flicker on every keystroke. CSS/content edits patch iframe DOM in place; only structural changes trigger full reload.
HTML Snippet Buttons — Quick-insert buttons on the HTML editor title bar: sec, div, h1-h3, p, a, img, ul, ol, span, b, i. Wraps selection or inserts empty.
Section Renaming — Double-click any section name in the sidebar to rename it inline.
SVG Icons — Replaces unicode glyphs for hide/duplicate/delete buttons.
Keyboard Shortcuts Overlay — ? button shows all shortcuts.
Export/Import — Download/upload sections as JSON, append or replace modes.

Preview Customization — New admin fields for custom CSS, head HTML, and footer JS injected into the preview iframe. No PHP filter needed for common cases.
AI default model changed from gpt-5.2 to claude-sonnet-4-6.

Script injection in preview iframe: Now injected post-load via contentDocument.createElement('script') instead of inline <script> in srcdoc. Fixes SyntaxError: Unexpected token '<' errors caused by </script> parsing in srcdoc HTML.
SVG icon click delegation: Uses closest('[data-action]') to traverse up from clicked SVG to the button.
HTTPS enforcement: All preview style URLs forced to https:// to eliminate mixed content warnings.
AI conversation history: All three providers (OpenAI, Anthropic, Gemini) properly send the message array.