docs: Obsidian-style vault under docs/

Add a navigable Obsidian vault as the project's first-class
technical documentation. Notes cross-reference with [[wikilinks]];
docs/index.md is the Map of Content.

New notes:
  index.md             MOC, entry point
  architecture.md      what the extension owns vs what lives outside
  data-model.md        entity-by-entity schema reference
  menu-tree.md         the arbitrary-depth tree concept
  order-flow.md        state machine + invoice listener + print
  nostr-layer.md       kinds 0/30402/5/1059, signing, t-tags
  api-reference.md     endpoint catalog by audience
  cms.md               Vue 3 + Quasar 2 UMD conventions, q-tree
  webapp-integration.md  multi-restaurant cart pattern + atomicity
  glossary.md          domain terms

Existing notes (kept as-is):
  adr-0001-menu-tree.md  the storage choice rationale
  design-conversation.md trimmed transcript

README.md adds a Documentation section pointing at docs/index.md
with the headline note list. Each note links to ~3-5 others; the
vault forms a connected graph.

A project-level memory rule (saved outside the repo) commits us to
keeping these docs in sync as the code evolves: any commit that
materially changes schema, API, order flow, Nostr surface, CMS
conventions, or webapp integration must update the relevant note(s)
in the same commit.

docs/cms.md

@@ -0,0 +1,88 @@
+# CMS
+
+The operator-facing console — what the restaurant owner sees when
+they enable the extension. Lives under `/restaurant/...` and uses
+LNbits' built-in **Vue 3.5 + Quasar 2.18 UMD** runtime: no build
+step, no bundler, just Jinja templates including a per-page JS file.
+
+## Pages
+
+All pages extend `base.html` (provided by LNbits core) and require a
+logged-in user (`check_user_exists`).
+
+| Path | Template | Script | Purpose |
+|---|---|---|---|
+| `/restaurant/` | `restaurant/index.html` | `static/js/index.js` | Restaurant list / dashboard |
+| `/restaurant/{slug}` | `restaurant/menu.html` | `static/js/menu.js` | [[menu-tree\|menu]] builder (q-tree) |
+| `/restaurant/{slug}/orders` | `restaurant/orders.html` | `static/js/orders.js` | Order monitor |
+| `/restaurant/{slug}/kds` | `restaurant/kds.html` | `static/js/kds.js` | Kitchen Display |
+| `/restaurant/{slug}/settings` | `restaurant/settings.html` | `static/js/settings.js` | Restaurant + extension settings |
+
+## Conventions
+
+- `{% extends "base.html" %}` and `{% from "macros.jinja" import window_vars with context %}`.
+- Page content goes in `{% block page %}`. Scripts in `{% block scripts %}`, after `{{ window_vars(user) }}`.
+- The page JS sets `window.app = Vue.createApp({mixins: [windowMixin], data, methods, created})`. LNbits' `init-app.js` runs after the extension scripts and finishes the mount with `app.use(Quasar)` + `app.mount('#vue')` — **don't call `.mount()` yourself**.
+- Bootstrap data is injected via `<script>window.X = {{ thing | tojson | safe }}</script>` between the macro and the per-page script.
+- The shared REST client is `static/js/api.js`, exposing `window.RestaurantAPI` (one method per resource).
+
+## Menu builder (q-tree)
+
+The menu page uses Quasar's `q-tree` directly off the hydrated tree
+returned by `GET /api/v1/restaurants/{id}/menu`. Three-pane layout:
+
+```
++--------------------+----------------+----------------------------+
+| sidebar nav        | q-tree         | Items panel                |
+| (orders / KDS /    |  with inline   |  (filtered by selected     |
+|  settings links)   |  edit buttons  |   tree node)               |
++--------------------+----------------+----------------------------+
+```
+
+Custom `default-header` slot renders:
+
+- node name + item-count badge + child-count hint
+- inline buttons: `add` (disabled at depth 3), `edit`,
+  `drive_file_move`, `delete` (with cascade prompt)
+
+Add-root button sits above the tree (`+ New top-level`).
+
+The Move dialog uses a flat-indented `q-select` of all nodes,
+filtered to exclude the moved node + its descendants and any
+depth-3 candidate. (The server enforces both checks too — see
+[[menu-tree]].)
+
+Drag-drop reorder is **v2**; v1 uses the explicit Move dialog.
+
+## Item dialog
+
+The item dialog includes a flat-indented `q-select` for `node_id`,
+populated by walking the tree with em-space indentation per depth
+level. An item can land on any node, not just leaves.
+
+Modifier groups + modifiers live in a separate dialog (a child of
+the item dialog) with the `chooseOne / chooseMany / required /
+optional` semantics from [[data-model|the data model]].
+
+## Order monitor + KDS
+
+Both use the same data source (`GET /restaurants/{id}/orders`)
+filtered by status. The KDS view escalates color by age (`>5min`
+orange, `>15min` red) and offers one-tap state transitions.
+
+Today the monitor + KDS poll every 5–8 s. SSE / Nostr push is on
+the roadmap.
+
+## Settings
+
+`settings.html` saves restaurant fields via
+`PUT /restaurants/{id}` and (for LNbits admins) extension-wide
+toggles via `PUT /settings`. NIP-17 orders toggle is currently
+disabled because the unwrap step is stubbed — see [[nostr-layer]].
+
+## See also
+
+- [[architecture]]
+- [[menu-tree]]
+- [[order-flow]]
+- [[api-reference]]