Bridge global catalogue DB to per-store product catalogue

Adds a separate CatalogueDB (pgvector) connection alongside the main
nearledb, plus a new catalogue module (repository/service/controller/
routes) to browse it by brand, category, and keyword, with brand
optional so the whole ~237-product catalogue can be browsed unfiltered.

Adds the actual bridge: importing a catalogue product snapshots it into
the tenant's own products table (keyed on brand+catalogueid, since a
catalogue row's bare id is only unique within its own brand table),
then links it via the existing productlocations upsert. Re-importing
tops up stock and refreshes price instead of duplicating. Also adds an
imported-refs endpoint so the frontend can badge already-imported items
without diffing full product lists, and wires the new AWS S3 image
store used to resolve catalogue product photos.

Bumps Go/Docker to 1.24 for the AWS SDK dependency this needs.

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

models/catalogue.go

@@ -0,0 +1,86 @@
+package models
+
+import (
+	"strings"
+	"time"
+)
+
+// CatalogueProduct maps to the per-brand tables (brand_dabur, brand_nestle, ...)
+// in the separate pgvector catalogue database. The `embedding` vector column
+// is intentionally not mapped here — it is never needed in an API response.
+type CatalogueProduct struct {
+	ID           int64         `json:"id"`
+	Brand        string        `json:"brand"`
+	ProductName  string        `json:"product_name"`
+	Title        string        `json:"title,omitempty"`
+	Description  string        `json:"description,omitempty"`
+	Category     string        `json:"category,omitempty"`
+	ImageID      string        `json:"image_id,omitempty"`
+	Images       []string      `json:"images,omitempty"`
+	Size         string        `json:"size,omitempty"`
+	VariantKey   string        `json:"variant_key,omitempty"`
+	ProductSKU   string        `json:"product_sku,omitempty"`
+	SKUSource    string        `json:"sku_source,omitempty"`
+	PriceRange   string        `json:"price_range,omitempty"`
+	Providers    PGStringArray `json:"providers,omitempty"`
+	FSSAILicense string        `json:"fssai_license,omitempty"`
+	Highlights   PGStringArray `json:"highlights,omitempty"`
+	Nutrients    PGStringArray `json:"nutrients,omitempty"`
+	SearchQuery  string        `json:"search_query,omitempty"`
+	CreatedAt    time.Time     `json:"created_at,omitempty"`
+	UpdatedAt    time.Time     `json:"updated_at,omitempty"`
+}
+
+// CatalogueBrand describes a brand available in the catalogue DB.
+type CatalogueBrand struct {
+	Brand        string `json:"brand"`
+	ProductCount int64  `json:"product_count"`
+}
+
+// PGStringArray is a plain []string used for catalogue array fields
+// (providers, highlights, nutrients) in JSON responses.
+type PGStringArray []string
+
+// ParsePGArray parses a Postgres text[] literal (e.g. "{Amazon,Flipkart}")
+// into a Go []string. GORM's raw-scan-into-struct silently drops slice-kind
+// destination fields, so array columns are queried as `col::text` and
+// converted with this function after scanning, rather than scanned directly.
+func ParsePGArray(s string) PGStringArray {
+	s = strings.TrimSpace(s)
+	if s == "" || s == "{}" {
+		return PGStringArray{}
+	}
+	if strings.HasPrefix(s, "{") && strings.HasSuffix(s, "}") {
+		s = s[1 : len(s)-1]
+	}
+
+	var result PGStringArray
+	var buf strings.Builder
+	inQuotes := false
+	escaped := false
+
+	for _, r := range s {
+		switch {
+		case escaped:
+			buf.WriteRune(r)
+			escaped = false
+		case r == '\\':
+			escaped = true
+		case r == '"':
+			inQuotes = !inQuotes
+		case r == ',' && !inQuotes:
+			result = append(result, buf.String())
+			buf.Reset()
+		default:
+			buf.WriteRune(r)
+		}
+	}
+	result = append(result, buf.String())
+
+	for i, v := range result {
+		if v == "NULL" {
+			result[i] = ""
+		}
+	}
+	return result
+}