Third tranche of the F-016 split. Extract the pmacs.mcp surface (MCP client
bindings) from src/lua_bindings/mod.rs into src/lua_bindings/mcp.rs,
verbatim.
Corrected model (see framing): a helper-hoist is NOT a prerequisite for
most domains. The contamination that stopped parse/theme bites only when a
shared helper is *defined inside* the range being extracted. A domain that
merely *uses* a cross-section helper reaches it via `super::`
(parent-private access). So mcp extracts cleanly: all its items are
self-contained, and it reaches the JSON converters (still in the lsp
section) via super::json_to_lua / lua_to_json, and SharedProcessSupervisor
via super::. The JSON-helper hoist is deferred to the tranche that
extracts lsp itself (where they're defined).
mod.rs declares `mod mcp;` and re-exports make_mcp_manager (external caller
editor.rs) and McpServerIdLua — the latter to preserve its public-API path
crate::lua_bindings::McpServerIdLua (moving it into a private module had
dropped it from the crate surface; the split must not shrink the public
API).
Pure code motion, no behavior change. mod.rs: 14603 → 14020 lines.
Validated: fmt clean; clippy --lib clean under both Lua flavors; full lib
suite 1437 passed / 0 failed under both luajit and lua54.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014TXbAwk27agwhrNNrhLi2U
