feat: support npm scoped package specifiers for plugins

Plugins can now be referenced as "@quartz-community/<name>" in
quartz.config.yaml and via 'quartz plugin add'. The npm path skips
git installation and resolves from node_modules.

Changes:
- gitLoader.ts: detect @scope/name as npm package in parsePluginSource()
- config-loader.ts: skip git install for npm packages, read manifests
  from node_modules via createRequire
- install-plugins.ts: filter npm packages from prebuild, fallback to
  YAML config parsing to avoid loading full quartz.ts
- plugin-data.js: npm detection in CLI parseGitSource()
- plugin-git-handlers.js: npm install path in handlePluginAdd()
- package.json: add missing hast-util-from-html dependency

quartz/cli/plugin-data.js

@@ -190,6 +190,11 @@ export function parseGitSource(source) {
       typeof source === "object" && source.name ? source.name : path.basename(parsed, ".git")
     return { name, url: parsed, ref, subdir }
   }
+  // Handle npm scoped packages
+  if (typeof url === "string" && url.startsWith("@") && url.includes("/") && !url.includes(":")) {
+    const name = typeof source === "object" && source.name ? source.name : url
+    return { name, url: "", npmPackage: true, subdir }
+  }
   throw new Error(`Cannot parse plugin source: ${formatSource(source)}`)
 }
 

quartz/cli/plugin-git-handlers.js

@@ -1,7 +1,7 @@
 import fs from "fs"
 import path from "path"
 import os from "os"
-import { exec as execCb } from "child_process"
+import { exec as execCb, execSync } from "child_process"
 import { styleText, promisify } from "util"
 import {
   readPluginsJson,
@@ -1190,6 +1190,15 @@ export async function handlePluginAdd(
   for (const source of sources) {
     try {
       const parsed = parseGitSource(source)
+      if (parsed.npmPackage) {
+        const name = nameOverride ?? parsed.name
+        console.log(styleText("cyan", `→ Installing ${name} from npm...`))
+        execSync(`npm install ${parsed.name}`, { cwd: process.cwd(), stdio: "inherit" })
+        const configSource = nameOverride ? { repo: parsed.name, name: nameOverride } : parsed.name
+        const pluginDir = path.join(process.cwd(), "node_modules", ...parsed.name.split("/"))
+        addedPlugins.push({ name, pluginDir, source: parsed.name, configSource })
+        continue
+      }
       const name = nameOverride ?? parsed.name
       const url = parsed.url
       const ref = parsed.ref