Move bierner.markdown-mermaid into core

[mjbvz]

This makes my mermaid markdown extension builtin. As part of this I've renamed chat-mermaid-features to the more generic markdown-mermaid-features since this once extension now contributes a consistent mermaid UX for chat, notebooks, and previews

Fixes #293028
Depends on #316329

[Copilot]

Pull request overview

This PR replaces the built-in Mermaid chat-only extension with a broader Mermaid Markdown extension that supports chat rendering, Markdown previews, and notebook Markdown output.

Changes:

• Adds a new mermaid-markdown-features extension with Markdown-it integration, preview scripts, notebook renderer support, chat renderer support, commands, configuration, and build scripts.
• Removes the old mermaid-chat-features extension and updates build/npm/lint references to the new extension name.
• Updates Copilot’s Ask agent tool reference to the new Mermaid renderer extension id.

Show a summary per file

File	Description
extensions/mermaid-markdown-features/package.json	Defines the new extension contributions, settings, commands, renderers, tools, and scripts.
extensions/mermaid-markdown-features/package.nls.json	Adds localized package/configuration strings.
extensions/mermaid-markdown-features/README.md	Documents the bundled Mermaid Markdown extension.
extensions/mermaid-markdown-features/tsconfig.json	Adds TypeScript configuration for extension sources.
extensions/mermaid-markdown-features/tsconfig.browser.json	Adds browser build TypeScript configuration.
extensions/mermaid-markdown-features/esbuild.mts	Adds Node extension bundling entrypoint.
extensions/mermaid-markdown-features/esbuild.browser.mts	Adds browser extension bundling entrypoint.
extensions/mermaid-markdown-features/esbuild.webview.mts	Adds webview/notebook/preview bundling.
extensions/mermaid-markdown-features/cgmanifest.json	Adds component governance manifest placeholder.
extensions/mermaid-markdown-features/.gitignore	Ignores generated Mermaid webview outputs.
extensions/mermaid-markdown-features/.npmrc	Adds npm install settings for the extension.
extensions/mermaid-markdown-features/.vscodeignore	Excludes source/build files from packaged extension output.
extensions/mermaid-markdown-features/src/extension.ts	Activates chat, commands, configuration refresh, and Markdown-it integration.
extensions/mermaid-markdown-features/src/chatOutputRenderer.ts	Renames chat renderer ids/commands and adds editor/context support.
extensions/mermaid-markdown-features/src/editorManager.ts	Renames editor preview view type and improves preview controls.
extensions/mermaid-markdown-features/src/webviewManager.ts	Adds shared command context typing for Mermaid webviews.
extensions/mermaid-markdown-features/src/markdownMermaid/markdownIt.ts	Adds Markdown-it parsing/highlighting support for Mermaid blocks.
extensions/mermaid-markdown-features/src/markdownMermaid/config.ts	Injects Mermaid preview configuration into rendered Markdown.
extensions/mermaid-markdown-features/src/util/dispose.ts	Adds disposable helpers for extension-side resources.
extensions/mermaid-markdown-features/src/util/html.ts	Adds HTML escaping helper.
extensions/mermaid-markdown-features/src/util/uuid.ts	Adds UUID helper for webview nonces/ids.
extensions/mermaid-markdown-features/preview-src/shared/index.ts	Adds shared Mermaid rendering/config/addon logic.
extensions/mermaid-markdown-features/preview-src/shared/diagramManager.ts	Adds shared pan/zoom/resize diagram UI management.
extensions/mermaid-markdown-features/preview-src/shared/diagramStyles.css	Adds shared Mermaid diagram control styles.
extensions/mermaid-markdown-features/preview-src/shared/config.ts	Defines shared preview configuration types.
extensions/mermaid-markdown-features/preview-src/shared/disposable.ts	Adds shared disposable interface.
extensions/mermaid-markdown-features/preview-src/shared/css.d.ts	Adds CSS module typing for preview bundling.
extensions/mermaid-markdown-features/preview-src/shared/iconPackConfig.ts	Registers icon packs for Mermaid diagrams.
extensions/mermaid-markdown-features/preview-src/markdown/index.ts	Adds Markdown preview Mermaid rendering bootstrap.
extensions/mermaid-markdown-features/preview-src/notebook/index.ts	Adds notebook Markdown Mermaid renderer integration.
extensions/mermaid-markdown-features/preview-src/chat/index.ts	Adds chat webview bootstrap.
extensions/mermaid-markdown-features/preview-src/chat/index-editor.ts	Adds editor preview control wiring.
extensions/mermaid-markdown-features/preview-src/chat/mermaidWebview.ts	Updates chat/editor pan-zoom handling with pan mode.
extensions/mermaid-markdown-features/preview-src/chat/vscodeApi.ts	Adds VS Code webview API typing.
extensions/mermaid-markdown-features/preview-src/chat/tsconfig.json	Updates chat webview TypeScript paths.
extensions/mermaid-chat-features/package.json	Removes the old Mermaid chat-only extension manifest.
extensions/mermaid-chat-features/package.nls.json	Removes old extension localization strings.
extensions/mermaid-chat-features/package-lock.json	Removes old extension dependency lockfile.
extensions/mermaid-chat-features/README.md	Removes old extension README.
extensions/mermaid-chat-features/src/extension.ts	Removes old extension activation code.
extensions/mermaid-chat-features/esbuild.webview.mts	Removes old webview build script.
extensions/mermaid-chat-features/.gitignore	Removes old generated-output ignore entry.
extensions/esbuild-webview-common.mts	Updates shared webview esbuild defaults.
extensions/copilot/src/extension/agents/vscode-node/askAgentProvider.ts	Points Ask agent Mermaid tool usage to the new extension id.
eslint.config.js	Updates lint project/file references for the renamed extension.
build/npm/dirs.ts	Updates npm install directory list for the renamed extension.
build/lib/extensions.ts	Updates extension media build script list.
build/gulpfile.extensions.ts	Updates extension compilation list.
build/filters.ts	Updates validation filters for generated Mermaid outputs.
.eslint-ignore	Ignores generated output folders for the new extension.

Copilot's findings

Files not reviewed (1)

• extensions/mermaid-chat-features/package-lock.json: Language not supported

Comments suppressed due to low confidence (1)

extensions/mermaid-markdown-features/preview-src/shared/diagramManager.ts:449

• The never value for markdown-mermaid.mouseNavigation.enabled is not honored here. Because this check only blocks the alt mode without Alt pressed, ClickDragMode.Never falls through and enables dragging without any modifier; wheel/Alt zoom is also still enabled. Please branch explicitly for Never so mouse navigation is disabled when the setting says so.

• Files reviewed: 37/51 changed files
• Comments generated: 5