refactor(cli): drop the copilot command handler's frontmatter method nothing calls #822

Problem

The copilot profile's commandsHandler declares a convertFrontmatter method (cli/src/contexts/tools/domain/profiles/copilot/profile.ts, lines 112-117 on next) that nothing calls. The commands capability is built with convertCommandFrontmatter directly (line 262), and the handler is only used for buildFilePath (lines 161 and 261). knip does not see unused methods on an object literal. The #799 mutation pass found it: its mutants can only survive.

Scope

• Delete commandsHandler.convertFrontmatter from the copilot profile.

Acceptance criteria

• Nothing under cli/src names commandsHandler.convertFrontmatter.
• Copilot's installed and built commands are unchanged: the copilot profile tests and the golden snapshots pass as they are.

Prior art in this repository

• The same file routes skills through skillsHandler.convertFrontmatter (line 256). Only commands bypass their handler.

Out of scope

• Making every profile route frontmatter through its handler.