MCP `asks_act` takes back a mute: `listen` brings a muted repository's asks back, as /asks/listen does #7219

For: a mute from a harness can be undone from the same harness. Today MCP can mute a repository but never unmute one.

asks_act (src/http/mcp/tools/asks_act.ts:7-11) offers mute but nothing that undoes it. The page's POST /asks/listen (src/web/studio/asks_page.ts:732) and the terminal's dashboard (src/tui/screens/dashboard.ts:722) call removeMutes (src/core/interactions.ts).

Done:

• [ ] asks_act accepts action: "listen" with repo (owner/name). It calls removeMutes for the caller only, and answers which repositories are listened to again.
• [ ] With no repo, listen refuses invalid. A repository the caller cannot read is not_found, and so is one that was not muted, so nothing leaks.
• [ ] The tool's doc names listen. bun scripts/mcp-tools.ts regenerates the tools table, and test/mcp-tools.test.ts passes.
• [ ] A new test/mcp-asks-listen.test.ts calls /mcp with a real token: mute a repository, see its asks leave asks, listen, and see them back. It also asserts that another person's mute is untouched.

Files: src/http/mcp/tools/asks_act.ts, one test, and the files the generator writes. Risk: low.