Closes #31982

Changes

1. Documented tui.json parallel plugin system (new section)

The skill only documented opencode.json and never mentioned that the TUI has its own tui.json config file with a separate plugin array — loaded by an independent plugin system (plugin/tui/runtime.ts). If a user removes a plugin from opencode.json but it's also declared in `tui.json$/, it keeps loading via the TUI side.

Adds:

• tui.json rows to the "Where files live" table
• New "TUI config (tui.json)" section with valid fields and the distinction between server plugins vs TUI plugins
• Note that /plugins panel lists TUI plugins only, not server plugins
• Updated skill description to mention tui.json$/, tui.jsonc`

2. Added tools (deprecated) to frontmatter field list

The tools field exists in the JSON Schema (as deprecated) but was missing from the allowed frontmatter fields list. Changed "unknown field" to "unrecognized field" for accuracy.

3. Documented MCP permission handling + "*" catch-all pattern

• Added a note that mcp is NOT a recognized permission key (MCP tools cannot be controlled via permission.mcp)
• Documented the "*" catch-all pattern as the correct way to restrict MCP tools on an agent
• Added the missing skill key to the known permission keys list