Align Windsurf docs with Devin Desktop

[chubes4]

Summary

• describe Windsurf/Cascade as Devin Desktop / Windsurf Cascade in generated docs
• keep the existing plugins/windsurf/ path for compatibility
• document why the legacy generated path remains in place

Fixes #77

Testing

• pnpm build
• pnpm verify

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Drafted and implemented the Devin/Windsurf docs and generated-label updates, then ran build and verification.

[chubes4]

Updated based on review direction: this now migrates the generated output from plugins/windsurf/ to plugins/devin-desktop/ instead of retaining the legacy directory.

The generated README still points users to Cascade's current ~/.codeium/windsurf/mcp_config.json destination because that is the documented app config path, but the repository output path is now Devin Desktop.

Verification after update:

• pnpm build
• pnpm verify