docs(demo): add demo concept, scenarios, data, guide and runbook docs

Documents the demo-productization work from this branch: the Northstar
Mobility fictional concept and scope, the five named scenarios and their
fixed records, the seed/date-anchoring strategy (including the real bug
it fixed), the in-app Demo Guide's design and the English-suggested-
questions decision, and an operational runbook covering 5/10-minute demo
flows, reset, Unraid redeploy and rollback. Updates README with current
test counts and pointers to the new docs.

README.md

@@ -12,6 +12,17 @@ design decision and visual evidence.
 
 All people, companies, vehicles, bookings and documents are synthetic. The workflows, validation, integrations, audit logging and access boundaries are intended to be real.
 
+## Demo
+
+The demo presents itself as **Northstar Mobility**, a fictitious Belgian camper/van
+rental company — the login screen, a permanent "Synthetische demo" indicator, an in-app
+guided tour (Demo Guide), a curated `/scenarios` overview, and an "Over deze demo" page
+all make the fictional context, synthetic-data status, and real-vs-simulated boundaries
+explicit without any verbal explanation. See `docs/demo-release/` for the full demo
+concept, the five named scenarios, the seed/date-anchoring strategy, the guided-tour
+design, and the operational runbook (5-minute and 10-minute demo flows, reset, redeploy,
+rollback).
+
 ## Scope
 
 The PoC implements:
@@ -77,6 +88,9 @@ and `artifacts/final-acceptance/summary.md` for the original M0–M7 acceptance
 - `artifacts/design-validation/` — baseline audit, Stitch direction references and implemented responsive captures.
 - `docs/functional-completion/` — the functional-completion audit and pre-work server baseline.
 - `artifacts/functional-completion/` — functional-completion acceptance evidence.
+- `docs/demo-release/` — demo concept, scenarios, seed/date-anchoring strategy, guided
+  tour, and runbook.
+- `artifacts/demo-release/` — demo-productization acceptance evidence.
 
 ## Quickstart
 
@@ -100,9 +114,9 @@ All defaults are configurable via `.env` (see `.env.example`).
 ## Quality gates
 
 ```bash
-make test    # backend: pytest (117 tests)
+make test    # backend: pytest (127 tests)
 make lint    # backend: ruff + mypy (strict, zero errors)
-make e2e     # frontend: Playwright end-to-end (37 tests, live stack required)
+make e2e     # frontend: Playwright end-to-end (56 tests, live stack required)
 ```
 
 Frontend build/typecheck: `cd frontend && npm run build` (`tsc -b && vite build`).