refactor!: switch to stateless HTTP transport

.github/ISSUE_TEMPLATE/bug_report.md

@@ -56,11 +56,10 @@ Configuration:
 - FIGMA_API_KEY: ****8pXg (source: cli)
 - PORT: 3333 (source: default)
 
-Initializing Figma MCP Server in HTTP mode on port 3333...
+Initializing Figma MCP Server in HTTP mode on 127.0.0.1:3333...
 HTTP server listening on port 3333
-SSE endpoint available at http://localhost:3333/sse
-Message endpoint available at http://localhost:3333/messages
-New SSE connection established
+StreamableHTTP endpoint available at http://127.0.0.1:3333/mcp
+StreamableHTTP endpoint available at http://127.0.0.1:3333/sse (backward compat)
 ```
 
 **MCP Logs**

CLAUDE.md

@@ -49,11 +49,10 @@ PRs are squash-merged, so the PR title becomes the commit message that release-p
 
 ### Transport Modes
 
-The server supports three transports (all configured in `src/server.ts`):
+The server supports two transports (configured in `src/server.ts`):
 
 - **stdio** — For direct MCP client integration (activated with `--stdio` flag or `NODE_ENV=cli`)
-- **StreamableHTTP** — Modern HTTP transport at `/mcp`
-- **SSE** — Legacy HTTP transport at `/sse` + `/messages`
+- **StreamableHTTP** — Stateless HTTP transport at `/mcp` (also served at `/sse` for backward compatibility with existing client configs)
 
 ### Core Data Flow
 

package.json

@@ -54,10 +54,10 @@
     "cleye": "^2.2.1",
     "cross-env": "^7.0.3",
     "dotenv": "^16.4.7",
-    "express": "^4.21.2",
+    "express": "^5.2.1",
+    "jimp": "^1.6.0",
     "js-yaml": "^4.1.1",
     "remeda": "^2.20.1",
-    "jimp": "^1.6.0",
     "zod": "^3.25.76"
   },
   "devDependencies": {