fix: per-site attribution needs its own column, not pickuplocationid

Caught by testing the previous commit against production: creating a booking
with a resolved site failed with

  pickupbookings_pickuplocationid_fkey
  FOREIGN KEY (pickuplocationid) REFERENCES appcustomerlocations(...)

pickuplocationid is the *customer's* saved address, a B2C concept. It never
referred to the client company's own kitchens or branches. The pre-existing
code that validated an incoming pickuplocationid against TenantLocation was
wrong on the same point and would have 500'd for any caller that used it — it
had simply never been called with a value.

Adds tenantlocationid to pickupbookings and consignments (nullable, indexed,
additive via AutoMigrate), carried across at pickup, and points the reporting
filter, the by_location breakdown and the Unattributed bucket at it.

The booking request accepts tenantlocationid, and still accepts
pickuplocationid as an alias so anything written against the earlier docs
starts working instead of failing.

Also gofmt on the two model files touched; booking.go was already failing.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/express-console-api.md

@@ -128,7 +128,7 @@ tenants at once aren't a meaningful report, so it 400s without one.
 
 The same rows appear as `by_location` inside `GET /admin/reports`.
 
-**Send `pickuplocationid` on bookings.** Attribution depends on it. The server
+**Send `tenantlocationid` on bookings.** Attribution depends on it. The server
 will try to recognise the site from the pickup coordinates (within 150m) or a
 matching address, but an explicit id is exact and always wins.
 
@@ -266,8 +266,8 @@ delivered, riderkms, ridercharges, dutyminutes }`.
 POST /admin/expressbooking
 {
   "tenantid": 13,                  // required; forced to your own tenant on client logins
-  "pickuplocationid": 15,          // a stored kitchen/branch — fills address, pincode and
-                                   // coords for you, and is what makes per-site reporting work
+  "tenantlocationid": 13,          // a stored kitchen/branch — fills address, pincode and
+                                   // coords for you, and is what per-site reporting groups by
   "customer_phone": "9876543210",  // creates a Guest customer if unknown
   "customer_name": "Ramesh",
   "deliveryaddress": "12 Cross Cut Road, Gandhipuram",
@@ -286,8 +286,12 @@ POST /admin/expressbooking
 
 Rules worth knowing:
 - `parcels` must be non-empty and `tenantid` must exist.
-- Pickup address + pincode are required **unless** `pickuplocationid` supplies them.
-- A `pickuplocationid` belonging to another tenant is rejected.
+- Pickup address + pincode are required **unless** `tenantlocationid` supplies them.
+- A `tenantlocationid` belonging to another tenant is rejected.
+- `pickuplocationid` is accepted as an alias for `tenantlocationid`, for anything
+  written against the earlier version of this doc. Prefer the new name: the
+  database column called `pickuplocationid` means something else entirely (the
+  B2C customer's saved address) and is not what per-site reporting uses.
 - **CityGate**: the pickup pincode prefix must be an open city — `641`
   Coimbatore, `600` Chennai, `560` Bengaluru, `500` Hyderabad, `629` Nagercoil.
   Any other prefix is refused at the middleware, before the handler runs.