The Claude Code and OpenCode plugins' `new <name> <words>` makes an app from the harness through MCP `new_app`, after the person confirms #7499

Intent: building a new thing starts from wherever the owner already works: one line in the harness makes the app, and the crew can be told what to build.

Done:

• [ ] plugins/claude-code/commands/forge.md and plugins/opencode/forge.ts's COMMAND gain new <name> <words>. Say the name and description back and ask the person to confirm. Only after yes, call new_app with name and description = the words, then relay the app's page and the next step in two lines.
• [ ] Both argument hints and both plugin READMEs list it.
• [ ] test/plugins.test.ts passes (every backticked tool is in toolNames(), with name and description added to NOT_TOOLS if needed). A new assertion fails if either plugin stops naming new_app.

Files: plugins/claude-code/commands/forge.md, plugins/claude-code/README.md, plugins/opencode/forge.ts, plugins/opencode/README.md, test/plugins.test.ts.

Risk: #7373 edits the same plugin texts. Both add one subcommand line.