Menu schema v3: variants as separate products, POS-ready fields

- variants split into their own menu_items whenever price differs
  (name + variant fields; 164 products, 24 variant groups)
- price back to number (whole rupees); no more '449/549' strings
- diet select (veg/nonveg/mixed) instead of nullable bool — PocketBase
  serializes empty bools as false, which misfiled mixed dishes
- new fields for POS: sku (unique GB-CAT-NNN), available (86 toggle),
  tax_category (default food-5-gst)
- migration 1788500100_menu_items_v3 replaces menu_items; resync via
  scripts/update-menu.mjs
- cards render 'Dish – Variant', badges from diet, hide unavailable

README.md

@@ -165,10 +165,27 @@ node scripts/update-menu.mjs
 ```
 
 The script **replaces** all `menu_categories` / `menu_items` records (deletes old, inserts
-new) and touches nothing else. Item prices are text, so ranges like `449/549` work;
-`group` (`veg` / `nonveg`) drives the dietary badge; `image` is an optional URL. Admin edits
-to menu records are overwritten by the next sync — treat this file as the menu's source of
-truth.
+new) and touches nothing else.
+
+### `menu_items` schema (POS-oriented)
+
+- `uid` — stable slug identity
+- `category` — slug → `menu_categories`
+- `name` / `variant` — variants are **separate products** whenever their price differs
+  ("Penne Arrabiata" + variant "Veg" ₹589 / "Chicken" ₹639); the POS can group by `name`
+- `description`
+- `price` — number, whole rupees (449 = ₹449)
+- `diet` — select: `veg` / `nonveg` / `mixed` (a bool can't be null in PocketBase, so mixed
+  items like Caesar Salad use `mixed`; the site renders no badge for it)
+- `pairing` — optional beer pairing
+- `tag` — badge chip; also carries same-price choice lists (e.g. "Malai / Angara")
+- `image` — optional URL
+- `sku` — unique POS code, `GB-<CAT>-<NNN>` (e.g. GB-MNC-014)
+- `available` — false hides the item from the site (86'd) without deleting it
+- `tax_category` — default `food-5-gst`; adjust per item for POS GST mapping
+
+Admin edits to menu records are overwritten by the next sync — treat `menu-data.mjs` as the
+menu's source of truth.
 
 ## Container environment