Align mcp-server-dev skills with claude.com/docs connector guidance (#1418)

- build-mcp-server: load llms-full.txt for Claude-specific context;
  add Phase 6 (test in Claude, review checklist, submit, ship plugin)
- references/auth.md: add Claude auth-type table, callback URL,
  not-supported list
- references/tool-design.md: add Anthropic Directory hard requirements
  (annotations, name length, read/write split, prompt-injection rule)
- build-mcp-app: add Claude host specifics (prefersBorder,
  safeAreaInsets, CSP) and submission asset specs; testing via
  custom connector
- build-mcpb: note remote servers are the recommended directory path

plugins/mcp-server-dev/skills/build-mcpb/SKILL.md

@@ -8,6 +8,8 @@ version: 0.1.0
 
 MCPB is a local MCP server **packaged with its runtime**. The user installs one file; it runs without needing Node, Python, or any toolchain on their machine. It's the sanctioned way to distribute local MCP servers.
 
+> MCPB is the **secondary** distribution path. Anthropic recommends remote MCP servers for directory listing — see https://claude.com/docs/connectors/building/what-to-build.
+
 **Use MCPB when the server must run on the user's machine** — reading local files, driving a desktop app, talking to localhost services, OS-level APIs. If your server only hits cloud APIs, you almost certainly want a remote HTTP server instead (see `build-mcp-server`). Don't pay the MCPB packaging tax for something that could be a URL.
 
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