docs(skill): restructure install guide — CLI/MCP first, add tool restrictions

[huacnlee]

Summary

• Reorder steps: connect to Longbridge platform (CLI or MCP) first, install Skill second — the old order had Skill as Step 1, which is useless without data access
• Lead intro with terminal-based AI tools (Claude Code, Codex, opencode, OpenClaw) as the recommended/quickest path
• Clarify CLI vs MCP framing: CLI = best experience but needs local install; MCP = easier, just a URL
• Add Known restrictions by tool section with clear guidance and screenshots:
  • Claude Desktop Chat mode: network whitelist blocks CLI/MCP — switch to Code tab instead (screenshot added)
  • Codex Cloud mode: same network restrictions — must select "Work locally" (screenshot added)
  • Claude.ai / ChatGPT.com web: redirect to Claude Desktop Code tab
• Add mainland China accelerated MCP endpoint (https://openapi.longbridge.cn/mcp) to English version
• Rename section heading "Connect your Longbridge account" → "Connect to the Longbridge platform"
• All changes synced across en / zh-CN / zh-HK

Test plan

• Preview skill install page in all three locales
• Verify screenshots render correctly
• Check all links resolve (CLI reference, Claude Desktop download)

🤖 Generated with Claude Code