feat: Implement Plugin Marketplace Manager and Client

- Added PluginMarketplaceManager to coordinate marketplace reads and manage installed plugins.
- Introduced PluginMarketplaceClient for fetching marketplace metadata.
- Implemented storage management for installed plugins using MemoryStorage.
- Added methods for installing, uninstalling, and enabling/disabling plugins.
- Created type definitions for PluginMarketplaceManager options and installed plugin records.
- Added support for fetching full marketplace catalog and individual plugin metadata.
- Included error handling for fetch operations and validation of plugin data.
- Updated index.browser.ts to export new modules and types.

dist/PluginMarketplaceClient.js

@@ -0,0 +1,94 @@
+/**
+ * Host-agnostic client for reading marketplace metadata.
+ */
+export class PluginMarketplaceClient {
+    constructor(options) {
+        this.indexUrl = options.indexUrl;
+        this.baseUrl = options.baseUrl;
+        this.fetchFn = options.fetchFn;
+    }
+    /**
+     * Fetches and validates marketplace index.
+     */
+    async fetchIndex() {
+        const response = await this.getFetchFn()(this.indexUrl);
+        if (!response.ok) {
+            throw new Error(`Failed to fetch plugin index: HTTP ${response.status}`);
+        }
+        return normalizePluginIndex(await response.json());
+    }
+    /**
+     * Fetches and validates single plugin metadata entry.
+     *
+     * @param pluginId - Identifier referenced by marketplace index.
+     */
+    async fetchPlugin(pluginId) {
+        const response = await this.getFetchFn()(this.buildMetadataUrl(pluginId));
+        if (!response.ok) {
+            throw new Error(`Failed to fetch plugin ${pluginId}: HTTP ${response.status}`);
+        }
+        return normalizePluginMetadata(await response.json(), pluginId);
+    }
+    /**
+     * Fetches full marketplace catalog.
+     *
+     * Entries that fail fetch or validation get skipped so host can still render
+     * rest of catalog.
+     */
+    async fetchPlugins() {
+        const index = await this.fetchIndex();
+        const results = await Promise.allSettled(index.plugins.map((pluginId) => this.fetchPlugin(pluginId)));
+        return results.flatMap((result) => (result.status === 'fulfilled' ? [result.value] : []));
+    }
+    buildMetadataUrl(pluginId) {
+        const trimmedBaseUrl = this.baseUrl.endsWith('/') ? this.baseUrl : `${this.baseUrl}/`;
+        return `${trimmedBaseUrl}${pluginId}.json`;
+    }
+    getFetchFn() {
+        if (this.fetchFn) {
+            return this.fetchFn;
+        }
+        if (typeof fetch !== 'function') {
+            throw new Error('No fetch implementation available for PluginMarketplaceClient');
+        }
+        return fetch;
+    }
+}
+function normalizePluginIndex(value) {
+    const record = asRecord(value, 'Plugin index payload must be object');
+    return {
+        version: asString(record.version),
+        updatedAt: asString(record.updatedAt),
+        plugins: Array.isArray(record.plugins)
+            ? record.plugins.filter((entry) => typeof entry === 'string')
+            : [],
+    };
+}
+function normalizePluginMetadata(value, fallbackId) {
+    const record = asRecord(value, `Plugin metadata for ${fallbackId} must be object`);
+    return {
+        id: asString(record.id) || fallbackId,
+        name: asString(record.name),
+        version: asString(record.version),
+        description: asString(record.description),
+        author: asString(record.author),
+        repository: asString(record.repository),
+        thumbnail: asString(record.thumbnail),
+        downloadUrl: asString(record.downloadUrl),
+        homepage: asString(record.homepage),
+        tags: Array.isArray(record.tags)
+            ? record.tags.filter((entry) => typeof entry === 'string')
+            : [],
+        addedDate: asString(record.addedDate),
+    };
+}
+function asRecord(value, message) {
+    if (!value || typeof value !== 'object' || Array.isArray(value)) {
+        throw new Error(message);
+    }
+    return value;
+}
+function asString(value) {
+    return typeof value === 'string' ? value : '';
+}
+//# sourceMappingURL=PluginMarketplaceClient.js.map