Add Motion: the go-to-market operating system on top of the ledger

The ledger answers which contracted capacity is sold, to whom, at what
margin. It says nothing about the motion — the repeatable practice that
turns a customer conversation into a scoped deployment, and turns that
deployment into something the next one reuses.

Motion is deliberately not a parallel entity tree. DEMAND_STAGES already
is the motion, so Motion binds reusable artefacts to the stages of a
demand deal that already exists: an engagement hangs off one deal,
cascade deleted, one per deal by unique constraint.

Nine closed kinds, each declaring which stages it serves, and a starter
library of twelve templates covering all eight open stages.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

apps/web/package.json

@@ -38,7 +38,9 @@
     "react": "^19.0.0",
     "react-dom": "^19.0.0",
     "react-hook-form": "^7.85.0",
+    "react-markdown": "^10.1.0",
     "react-router-dom": "^7.1.1",
+    "remark-gfm": "^4.0.1",
     "sonner": "^2.0.8",
     "streamdown": "^2.5.0",
     "tailwind-merge": "^2.6.0",