Add the assistant tool registry and its first tool

Phase 1 of Nearle Buddy: an agent names a tool, and the registry decides
whether that is allowed, whether the arguments make sense, who is asking,
and what gets recorded — then runs a handler a person wrote and tested.

No agent gets raw table access. The usual argument for tools over
generated SQL is safety; here there is a harder one. The fields on this
backend do not mean what their names say, and it is measured:
orders.deliverystatus is an empty string on all 181 rows of tenant 1147,
orders.orderstatus never carries the six middle delivery stages,
deliveries.ridername holds statuses as often as names, deliverytype is
empty on every row in production. A model writing SQL gets each of those
wrong with no error — it reports a cancel rate from a column of empty
strings and nobody can tell. A model calling a tool cannot, because the
correction lives in the handler beside the measurement that justified it.

Call does five things in order: find the tool, check the agent's
allow-list, validate arguments, confirm the caller is scoped to
something, run the handler — writing exactly one audit row whatever
happens, refusals included. A trail of successes answers "did anything
try to read another tenant?" with silence, which reads the same as no.

The model has no say in whose data is read. stuck_orders has no tenantid
field on its schema — absent, not rejected — and the tenant comes from
the session claims added in the previous commit. Arguments the tool did
not declare are dropped rather than passed on, so a model sending a
`where` clause gets it discarded.

stuck_orders: deliveries a rider was given and has not accepted, ten
minutes for a look, twenty-five for somebody now. Derived from assigntime
and orderstatus, so it does not depend on anyone having been watching.
Carries the wait in minutes, what to do, where to check it, and what it
covered. A capped answer says so — an empty result and a truncated one
look identical to a model and it will call both "none".

The audit sink writes to the log for now; a database sink is phase 8.
Nothing calls the registry yet: the loop and the model gateway are phase 2.

37 tests.

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

facade/container.go

@@ -4,6 +4,7 @@ import (
 	"nearle/controllers"
 	"nearle/repositories"
 	"nearle/services"
+	"nearle/services/tools"
 	"nearle/utils"
 
 	"gorm.io/gorm"
@@ -25,6 +26,13 @@ type Facade struct {
 	CatalogueUploadController *controllers.CatalogueUploadController
 	ScanController            *controllers.ScanController
 
+	// Tools is what Nearle Buddy is allowed to do.
+	//
+	// Held on the facade because the assistant is not a module with a
+	// repository of its own — it is a door onto the services already built
+	// here, and every tool handler calls one of them rather than the database.
+	Tools *tools.Registry
+
 	// Held so the NATS consumer can reach the ingest without going through
 	// HTTP. Unexported: everything else should use the controller.
 	posService services.PosService
@@ -119,6 +127,22 @@ func NewFacade(db *gorm.DB, catalogueDB *gorm.DB, embedder utils.Embedder) *Faca
 	scanService := services.NewScanService(scanRepo, embedder)
 	scanController := controllers.NewScanController(scanService)
 
+	// The assistant registry. Built last, because every tool it holds is a thin
+	// wrapper over a service constructed above.
+	//
+	// A registration error panics rather than being logged. A duplicate name or
+	// a tool with no description is a programming mistake, and a server that
+	// starts with a tool silently absent answers real questions with "I cannot
+	// do that" for a reason nobody can see from the outside.
+	toolRegistry := tools.New(tools.LogAudit{})
+	for _, tool := range []tools.Tool{
+		tools.StuckOrders(deliveriesService, nil),
+	} {
+		if err := toolRegistry.Register(tool); err != nil {
+			panic("assistant tools: " + err.Error())
+		}
+	}
+
 	return &Facade{
 		UserController:            userController,
 		ProductController:         productController,
@@ -134,6 +158,7 @@ func NewFacade(db *gorm.DB, catalogueDB *gorm.DB, embedder utils.Embedder) *Faca
 		LiveController:            liveController,
 		CatalogueUploadController: catalogueUploadController,
 		ScanController:            scanController,
+		Tools:                     toolRegistry,
 		posService:                posService,
 	}
 }