feat(TRUEREF-0011): implement MCP server with stdio transport

Adds a Model Context Protocol server that exposes resolve-library-id
and query-docs tools via stdio, with tool schemas identical to context7
for drop-in compatibility with Claude Code, Cursor, and Zed.

- src/mcp/index.ts — server entry point (io.github.trueref/trueref)
- src/mcp/client.ts — HTTP client for TrueRef REST API (TRUEREF_API_URL)
- src/mcp/tools/resolve-library-id.ts — library search tool handler
- src/mcp/tools/query-docs.ts — documentation retrieval tool handler
- src/mcp/index.test.ts — integration tests spawning real server subprocess
- .claude/rules/trueref.md — Claude Code rule file for MCP usage
- package.json: mcp:start script using tsx

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/mcp/index.ts

@@ -0,0 +1,84 @@
+/**
+ * TrueRef MCP Server — stdio transport
+ *
+ * Exposes resolve-library-id and query-docs tools, identical to context7's
+ * MCP interface, for drop-in compatibility with Claude Code, Cursor, and
+ * other MCP-aware AI coding assistants.
+ *
+ * Configuration:
+ *   TRUEREF_API_URL  Base URL for the TrueRef REST API (default: http://localhost:5173)
+ *
+ * Usage:
+ *   npx tsx src/mcp/index.ts
+ */
+
+import { Server } from '@modelcontextprotocol/sdk/server/index.js';
+import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
+import {
+	CallToolRequestSchema,
+	ListToolsRequestSchema
+} from '@modelcontextprotocol/sdk/types.js';
+
+import {
+	RESOLVE_LIBRARY_ID_TOOL,
+	handleResolveLibraryId
+} from './tools/resolve-library-id.js';
+import { QUERY_DOCS_TOOL, handleQueryDocs } from './tools/query-docs.js';
+
+// ---------------------------------------------------------------------------
+// Server setup
+// ---------------------------------------------------------------------------
+
+const server = new Server(
+	{
+		name: 'io.github.trueref/trueref',
+		version: '1.0.0'
+	},
+	{
+		capabilities: { tools: {} }
+	}
+);
+
+// ---------------------------------------------------------------------------
+// Tool registry
+// ---------------------------------------------------------------------------
+
+server.setRequestHandler(ListToolsRequestSchema, async () => ({
+	tools: [RESOLVE_LIBRARY_ID_TOOL, QUERY_DOCS_TOOL]
+}));
+
+// ---------------------------------------------------------------------------
+// Tool dispatch
+// ---------------------------------------------------------------------------
+
+server.setRequestHandler(CallToolRequestSchema, async (request) => {
+	const { name, arguments: args } = request.params;
+
+	if (name === 'resolve-library-id') {
+		return handleResolveLibraryId(args);
+	}
+
+	if (name === 'query-docs') {
+		return handleQueryDocs(args);
+	}
+
+	return {
+		content: [{ type: 'text' as const, text: `Unknown tool: ${name}` }],
+		isError: true
+	};
+});
+
+// ---------------------------------------------------------------------------
+// Startup
+// ---------------------------------------------------------------------------
+
+async function main() {
+	const transport = new StdioServerTransport();
+	await server.connect(transport);
+	// Server runs until process exits
+}
+
+main().catch((err) => {
+	process.stderr.write(`MCP server error: ${err instanceof Error ? err.message : String(err)}\n`);
+	process.exit(1);
+});