Add deps-map component and related command

docs/.vitepress/deps-map.data.js

@@ -0,0 +1,23 @@
+import { readFileSync, existsSync } from 'node:fs'
+import { resolve, dirname } from 'node:path'
+import { fileURLToPath } from 'node:url'
+
+const __dirname = dirname(fileURLToPath(import.meta.url))
+const DATA_PATH = resolve(__dirname, 'deps-data.json')
+
+export default {
+  watch: [DATA_PATH],
+
+  load() {
+    if (!existsSync(DATA_PATH)) {
+      console.warn(
+        '[deps-map.data.js] deps-data.json not found. ' +
+        'Run `bin/spc dev:gen-deps-data` to generate it.'
+      )
+      return { packages: {}, missing: true }
+    }
+
+    const raw = JSON.parse(readFileSync(DATA_PATH, 'utf-8'))
+    return { packages: raw.packages ?? {}, missing: false }
+  },
+}