feat(conversation): CHAT-03 I1, mediated control of a sealed headless Pi (#1507)

Controller, claim store, live-session guard, engine link and seal,
turn tracker, cohort force stop and recovery, client library,
transcript and mediated terminal, with the fake engine and tests.
Fixtures only; no live cutover.

Dewey built it. Darkwing (comment 26690) and Filbert (comment 26694)
approved round 2. Manifest I1-r2-manifest.sha256 (2b48e333, 27 files).
Suites on an export: conversation 152/152, control-board 124, webui 14,
seat 19, chat-00/01/01c checks, and all nine scripts/test-*.sh green.
Follow-ups for I3 are in DEFERRED. Gate E stays with Jason.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

packages/conversation/package.json

@@ -2,10 +2,16 @@
   "name": "@mosaic/conversation",
   "version": "0.1.0",
   "private": true,
-  "description": "Read-only Pi conversation histories for the Console: approved roots, safe opens, branch pages and cursors. No server; the control board serves it.",
+  "description": "Pi conversations for the Console: read-only histories (CHAT-02) and mediated control of a sealed headless Pi through a local controller, client library and terminal (CHAT-03 I1, fixtures only).",
   "license": "UNLICENSED",
   "type": "module",
   "engines": { "node": ">=24" },
-  "exports": { ".": "./src/reader.mjs" },
+  "exports": {
+    ".": "./src/reader.mjs",
+    "./controller": "./src/controller.mjs",
+    "./client": "./src/client.mjs",
+    "./transcript": "./src/transcript.mjs",
+    "./terminal": "./src/terminal.mjs"
+  },
   "scripts": { "test": "node --test tests/" }
 }